Talk:Greenhouse effect/Archive 2

Convection

The claim that the greenhouse effect works by blocking convection is absurd. That's like saying a tea kettle works by blocking drainage. It says nothing about what drives the temperature up. (With your windows and doors closed, your home also acts as a barrier to convection, but that doesn't make it a greenhouse.) Consequently, the claim on this page that the term "greenhouse effect" is a misnomer is also incorrect. The description there of how a greenhouse works makes no mention of how the glass blocks the transmission of infrared radiation. This is confusing and misleading. I first encountered these claims on a web site funded by the oil industry that professed to "explain" the greenhouse effect but only clouded the issue (If you'll excuse the expression). (I first raised this point in the Solar greenhouse (technical) discussion, but this seems to be a better place for it.) --MiguelMunoz 18:38, 28 July 2006 (UTC)

I am sorry Miguel, but you are mistaken. The greenhouse effect describes processes by which the heat generated by solar radiation is trapped near the surface of the Earth. For the Earth as a whole, this is accomplished primarily (but not exclusively) by the absorption of infrared radiation by greenhouse gases in the atmosphere. However, for the greenhouses that we build, heat is trapped near the surface primarily (but not exclusively) by the enclosed space which prevents the warmed air from rising to mix with other, cooler portions of the atmosphere. People can build a perfectly functioning greenhouses with materials that are totally transparent to infrared. Talk:Greenhouse effect/Archive 1 and Talk:Solar greenhouse (technical)/Archive 1 have some very long (and argumentative) discussions of this. Dragons flight 19:10, 28 July 2006 (UTC)

On People can build a perfectly functioning greenhouses with materials that are totally transparent to infrared, see http://www.wmconnolley.org.uk/sci/wood_rw.1909.html William M. Connolley 20:21, 28 July 2006 (UTC)

Miguel - I don't understand either of the points you are trying to make.

"The claim that the greenhouse effect works by blocking convection is absurd.". The article is very clear that the greenhouse effect works by the absorption of infra red radiation. It is only the glass structure used in gardening (a glasshouse to give it an old fashioned name) that works by blocking radiation. This is mentioned towards the end of the article after an extensive discussion of radiative transfer.

Secondly I can't see why you claim "It says nothing about what drives the temperature up" when the second sentence of the Real Greenhouses section states "it heats up primarily because the Sun warms the ground inside it". If this was not mentioned your analogy with a home would be valid - however the source of the heat is mentioned as well as the mechanism by which the heat is inhibited from escaping.

I would however add that I think it is a mistake to mention glasshouses in the lead section and some mention of IR there might be useful.--NHSavage 20:57, 29 July 2006 (UTC)

Okay, I also take issue with the claim that the greenhouse effect is so named because of an incorrect analogy with the functioning of a greenhouse. While it may be true that functioning greenhouses can be built without materials that trap re-radiation of infrared, it is nevertheless the case that a significant portion of greenhouses use more standard IR-blocking materials, and that a significant portion of their heat comes from that process. In fact, the article about greenhouses on this very site explains the heating mechanism in terms of trapping re-radiated IR, so to call the analogy false creates a lot of confusion. Perhaps a better statements would be "the greenhouse effect's name come from an analogy to one of the mechanisms that heats up real greenhouses". This sentence doesn't mislead people about the functioning of greenhouses, or about the connection between them and the greenhouse effect.

it is nevertheless the case that a significant portion of greenhouses use more standard IR-blocking materials, and that a significant portion of their heat comes from that process. - who says that a significant portion of their heat comes from that process - you? I'm afraid you;ll need rather better than an unsupported assertion, no matter how "obvious" is may be to you. Solar greenhouse (technical) does *not* say that IR trapping is a major effect - it says, just like this page, that first is the stopping convection and only second is IR William M. Connolley 19:39, 17 November 2006 (UTC)

Cleanup

This article seriously needs cleanup. --scienceman 17:04, 25 July 2006 (UTC)

WH nonsense

I deleted http://www.warwickhughes.com/icecore/. Not only is it rubbish, its also misleading: despite purporting to be a statement given in evidence, it wasn't William M. Connolley 15:52, 28 September 2006 (UTC)

"Real greenhouses"

As far as I can see the section "Real greenhouses" is misleading, incorrect and should be removed. In order for something to be warmer than its surroundings there has to be some phenomenon that makes it warmer. That phenomenon is (roughly speaking) that it lets sunlight through, but not the blackbody radiation from the earth. In order to keep it warmer than its surroundings you have to restrict the transport processes that otherwise will cool it until it reaches the temperature of the surroundings (in this case the glass structure that keeps it from mixing with the surrounding air). That is however not the primary reason for the warmer climate within a greenhouse, it is just a condition. If you leave a house (or any other closed volume with the about the same properties as the surroundings) unheated for a reasonably long period the temperature within the house will not differ from its surroundings.

One of the two links given do actually deal with finding errors in Mr Wood's argument (no. 7 at the moment), while the other one is a rather political page of low quality. Gunnar Larsson 18:32, 16 October 2006 (UTC)

First of all, this has been extensively discussed. Its one of the few points of fact that have an arbcomm ruling in their favour. But we can still talk about it... AFAIK "bad greenhouse" doesn't point to any errors in Wood; be so kind as to quote the piece you have in mind. If the other "low quality" page is mine I fear I disagree with you; I point out the only flaw I know of in Woods paper.

But on to your: That phenomenon is (roughly speaking) that it lets sunlight through, but not the blackbody radiation from the earth. This is simply a bald and unsupported assertion. From a theoretical point of view its a possibility; however, observational evidence is against it. You are correct in your restrict the transport processes that otherwise will cool it - and the transport process that is restricted is movement of heat by movement of air: direct thermal advection. I don't understand your house bit: if you mean, a closed volume with few openings for light, then yes of course: because there is no internal heating from sunlight William M. Connolley 19:15, 16 October 2006 (UTC)

Real greenhouses 1

I don´t know whether the Wikipedia´s section "Real greenhouses" was written based on IPCC background or is independent, however, in both cases almost all of the section´s concepts are completely wrong, as demonstrated below:

1st. The greenhouse effect is NOT a misnomer! Both the atmospheric greenhouse effect and real greenhouses have very very similar behaviours.

2nd. The real greenhouses do NOT suppress convection!

3rd. The comparison of the atmospheric greenhouse effect with that from a real agricultural or for home heating greenhouse is CORRECT, but not complete. The more complete or more correct comparison should be made with another type of greenhouse called "solar still", where there is also a water surface and evaporation.

4th. In fact, a greenhouse, in comparison with an equivalent open system REDUCES the convection, but NOT only the convection! Besides the convection, also the radiation and evaporation emissions from bottom to top of the system decrease. Contrary to these three modes, the conduction heat transfer from bottom through the soil increases, due to the higher soil or water temperatures attained in greenhouse systems. These explanations are clearly shown in Sartori (1996)*, whose paper seems to be the only one in the world that compares scientifically the behaviour of an open solar evaporation system with a closed one (solar still), where the greenhouse effect takes place. With some identifiable differences, the behaviours of such systems are very similar to those of the atmosphere when it is more open and when it is more closed.

• Sartori, E. Solar still versus solar evaporator: a comparative study between their thermal behaviours. Solar Energy, 56/2, 199-206, (1996).

5th. The real greenhouse does NOT suppress the turbulent mixing! The IPCC or Wikipedia demonstrate not having the proper basic scientific background to know that from an open to a closed system (greenhouse) the convection is NOT suppressed, but only converted from FORCED to FREE convection while the turbulent flow CONTINUES working! I work theoretically and experimentally with such systems and there are scientific works that show this clearly, including experimental ones that show this through flow visualizations where the turbulent mixing is clearly observed.

6th. In the atmosphere, the Sun ALSO heats up the soil or water surfaces, which warms up the air in contact with them through convection. And when the sky is completely cloudy, this air is prevented from flowing away directly beyond the cloud cover. Directly means NOT changing the original convection process, because within the clouds happen different convection processes from the one that brings up the air from ground to the cloud cover. Thus, when the sky is more open, there is a small greenhouse effect, but when there is a strong cloud cover the greenhouse effect is much higher (with the constant amount of CO2, CH4 and other gases), as shown in Sartori (1996) and in http://noparadoxes.tripod.com.

7th. The ingenuous scientific background of the Wikipedia´s section "real greenhouses" is tremendous! Opening a window of a greenhouse does NOT correspond to a proof of the convection suppression! ON THE CONTRARY, when you open such a window the free convection inside the greenhouse is replaced by the forced convection, which withdraws more heat from indoors than before when the window was closed. Because more heat flows to outdoors, then the inner temperature decreases, and this process corresponds and is a consequence of the Second Law of Thermodynamics.

8th. Even in agricultural greenhouses where there isn´t free water surfaces the convection is NOT suppressed! Whenever and wherever there is a temperature difference there is convection! Thus, almost never you will have a suppression of convection naturally. This is a tremendous elemental concept of the heat transfer area that I don´t believe that such Wikipedia section was written by specialists. Worst if such elemental erroneous concepts are adopted by the IPCC.

9th. Almost all of the concepts of the Wikipedia´s section "Real greenhouses" are completely erroneous and incomplete and do not contribute to the advance of the understanding of the greenhouse effect, and must be withdrawn from the page in order to really give a contribution to the true science.

10th. In the article http://noparadoxes.tripod.com the author demonstrates lots and lots of errors contained in the essential concepts utilized by climatologists since more than a century ago, errors very similar to those contained in the section "Real greenhouses". Thus, it will not be a surprise if someday we know that the concepts shown in the Wikipedia´s section "Real greenhouses" are also adopted or were inspired by the IPCC, which is formed essentially by climatologists. —Preceding unsigned comment added by 201.86.243.200 (talk) 22:48, 2 December 2007 (UTC)

The relative roles of convection, conduction, evaporation and emission for GH temps

I know this is a sore point on this discussion, but there is a relatively simple experiment that illustrates the importance of emission and selective surfaces for the heating of greenhouses. Take two pieces of blued steel (coated in a fine layer of black iron oxide) and paint one with black paint. Leave both out in the sun with no covering. Carefully touch both with your finger.

The unpainted iron will probably burn your fingers, the painted one will be just warm.

Why is it so? The black iron is a good selective surface, having very little absorbtion (and thus emittance) of thermal IR. Black paint, on the other hand, is close to a black body (usually consisting of carbon black) and radiates lots when it gets hot.

Thus, for collecting heat you want to stop the emission of IR but allow the absorbtion of PAR.

This is not the full story, however. Plants themselves do not thrive when the ground is warm and the leaves are cold, as most of the chemical action takes place in the leaves. Thus, we wish to transfer heat collected from the sun to the air around the leaves. We might try to do this by putting a large selective surface under the plants, but in practice although the collector would get hot, much of the heat would be lost to surrounding air by convection. Thus, we trap the air in a box (and for other reasons too).

Another important source (currently not mentioned in the article) of heat loss in greenhouses is evaporation. Losing half a gram of water a second as vapour is more heat loss than the maximum heating effect on a square metre of direct sunlight. Controlling this is thus very important. Plants naturally try to evaporate water as part of their living process.

Finally, we have conduction. Glazings generally are very poor insulators, being so very thin. More significant is the boundary layer of air, but inside a greenhouse we lose half of this to condensation (as water vapour happily crosses the boundary layer by diffusion). Thus double wall films are quite effective.

So, it is true that IR emission is very important for efficient collection of light energy, and important for reducing losses at night, but convection and water vapour transfer is far more effective at cooling a greenhouse. My double walled, TIR blocking greenhouse is cool in summer simply by opening a 1m² hole in each end and relying on the cooling effect of evaporation, driven by convection. Thus, controlling air movement is the first priority of greenhouse design. Once you have sealed everything up, then you look at TIR for further thermal storage.

We might ask what the best use of a dollar for improving greenhouse heating costs is. Experience is that we should, in order, a) remove all air leaks, b) use IR blocking films, c) reduce conduction with extra layers. Thus, the options on commercial greenhouses are usually a) cheap UV only film, b) UV and IR film, c) double layer designs. Because of the massive effect of air transfer, this is assumed to be controlled first. My greenhouse rep tells me that until the relatively recent development of good IR PE films, polyethylene films with only UV block were the most commonly used. Recent advances in IR coatings have made these now commercially viable for growers.

Finally, there are 90% PAR transmitting woven cloths that block both UV(for longer life and human protection) and TIR(due to the kind of plastic) but allow significant air movement. These are commonly used in Australia for growing certain kinds of Orchid. Although 90% of the energy of the sun is reaching the ground, the large air transfer means that these environments only heat very slightly above ambient, and cool very quickly at night. Their multi-layer woven design means they should be quite good at blocking TIR(there are no visible holes through).

Regarding the real greenhouse effect, clearly convection, conduction and latent heat do not cross space, but do have an effect on global temperatures by moving heat from ground level where the light is absorbed to the upper surface where there is less insulating TIR blocking gas. I do not know anything about the importance and magnitude of that and will leave discussion to experts. -- njh 09:56, 18 October 2006 (UTC)

{{sprotected}}

Right now, it is semi-protected, so IP users may register and do something so disruptive that it may get heavier than it sounds. Even with "calmer" edits, we can't unprotect it without entering a request in wikipedia:requests for page protection nor can we remove the tag until a season or so. Agree? --Gh87 06:39, 28 October 2006 (UTC)

Anon Q

An anon asks (but did it by rubbing out another anon Q, so I've (William M. Connolley 16:34, 9 November 2006 (UTC)) re-added it here):

what about the greenhouse effect, not always associated with the earth's atmosphere?

what about the greenhouse effect which is linked to heat transfer?

--Jan Lindstrom ----

According to the IR-transmission spectrum, CO2 is an effective absorber. Parts of the window indicate 100% absorption (is this really true?). If so, what is all the CO2 fuzz about? Surely an increase in CO2 will not have any influence on climate, i.e. the spectrum window is already "saturated". Please, correct me on this or else I´ll turn into a skeptic.

You seem to have answered your own question. Only parts are saturated William M. Connolley 12:16, 21 November 2006 (UTC)

"Skeptics" try to argue it both ways. First, that there is not enough CO2 to absorb enough IR to affect the climate. Secondly, that the CO2 is saturated. In fact, the rest of the atmosphere acts as a sink for the CO2 to "desaturate" it; IR is absorbed by the CO2, the heat is transferred to the nitrogen/oxygen; repeat. This is not something that the IPCC stupidly overlooked. Gzuckier 15:53, 21 November 2006 (UTC)

runaway again

The current section on runaway greenhouse is badly confused and confusing. Its not even clear in what sense the term is being used. Or even if it has an accepted definition. Its clear the Earth has never had a runaway GHE or we wouldn't be here. If the Permian stuff was caused by GHE - and that isn't at all clear - it was merely positive feedbacks leading to an large increase - this is something entirely different. I think the section should be drastically trimmed William M. Connolley 23:26, 22 November 2006 (UTC)

Positive feedbacks can't last forever. No article wich use the term "runaway" said that they could.

The term "runaway greenhouse effect" is present in 347 articles according to scholar.google

http://scholar.google.com/scholar?q=%22runaway+greenhouse+effect%22&hl=en&lr=&ie=ISO-8859-1&btnG=Search

We can obvisouly see that the term "runaway" is only employed when there is a large positive feedback (when the series diverge until no more A gas can be supplied).

I propose a new title: positive feedback and a runaway greenhouse effect Touisiau 01:54, 23 November 2006 (UTC)

Thank you very much for including the Runaway Greenhouse Effect topic. Two years ago, I could not find any scientific research covering this topic. As global temperatures continue to increase, it becomes extremely relevant to the real-world. --Diego Bank (talk) 21:57, 1 January 2008 (UTC)

Based on this table

Gas removed	percent reduction in GE
H2O	36%
CO2	12%
O3	3%

(Source: Ramanathan and Coakley, Rev. Geophys and Space Phys., 16 465 (1978)); see also [1].

Maybe we should add a crucial information that global warming is inevitable because even if we could remove CO₂ completely from the atmosphere (which we couldn't), we couldn't remove all water vapor from the atmosphere. Meaning that even if we all stopped driving cars tomorrow, the Antarctica will still melt down to water by 2050. --Koramil 02:25, 9 January 2007 (UTC)

Simply because they cause the greenhouse effect doesn't mean they'll cause global warming. If it weren't for other factors, the world would stay at a steady temperature if the amount of greenhouse gases stayed constant. Those gases are needed to keep the earth at a steady temperature, without them we'd be up an average of 30^oC colder. That would suck. Don't blame greenhouse gases for doing their job, they're not the problem. --Calibas 05:36, 9 January 2007 (UTC)

nonsense

The greenhouse gas theory is nonsensical. If carbon dioxide and water vapor reradiate some IR back to us, then the molecules are likewise reradiating out some of the incoming IR from the sun. These molecules are just as likely to cool us as warm us. It makes much more sense to me to blame temperature variations on the source of the radiation. The sun. —The preceding unsigned comment was added by 132.5.72.9 (talk) 22:56, 14 February 2007 (UTC).

That's nice, I always like to get input from people who obviously know nothing about the basic physics of the subject, aren't motivated to research the subject, and aren't ashamed to demonstrate their stubborn refusal to learn anything. Gzuckier 18:26, 15 February 2007 (UTC)

Is that all you have to say Gzuckier? Apart from the IR reradiation not being a logical reason for warming the planet, carbon isotopes and oxygen isotopes found in sediments indicate that carbon dioxide levels do not correlate to climate. 450 million years ago, the Earth was in the middle of an ice age and carbon dioxide levels were significantly higher than they are today. Even more importantly, the carbon dioxide levels were consistently high for millions of years as the Earth's climate oscillated between hot and cold. This alone seems to disprove the whole greenhouse gas theory.

http://en.wikipedia.org/wiki/Image:Phanerozoic_Climate_Change.png

http://en.wikipedia.org/wiki/Image:Phanerozoic_Carbon_Dioxide.png132.5.72.9 18:12, 20 February 2007 (UTC)

Sorry, User:132.5.72.9, but you've misunderstood the basic science. Incoming radiation from the sun is at different wavelengths - principally in the visible part of the spectrum - and the atmosphere is basically transparent to those wavelengths. It's the difference in effective temperature between the incoming solar and the outgoing terrestrial radiation that makes the greenhouse effect exist.

There is a whole body of science on this that is very well developed. If you are serious about understanding the science, here's a link to an online draft of a textbook on this. Pierrehumbert goes through all the steps in a clear and thorough way. Although I'm afraid there is a lot of math needed, you could skip the equations and still get a lot out of the narrative:

http://geosci.uchicago.edu/~rtp1/ClimateBook/ClimateBook.html

As for the phanerozoic, we have only the thinnest of clues what the earth was like that long ago. I think a more relevant comparison is the last 1 million years, during which CO2 and temperature are very tightly correlated. Correlation doesn't prove causation, but it certainly is consistent with it. But the history is not the only basis for the greenhouse theory - there is basic physics behind it, as Pierrehumbert explains.Birdbrainscan 03:56, 4 March 2007 (UTC)

There is also a large body of science on people who read an article or two on a subject, and then are motivated not only to believe that they know more than the entire body of individuals who have studied it professionally all their lives, but to tell all the world that those people are just "nonsensical". (Note that even the folks who oppose the AGW theory don't cite "then the molecules are likewise reradiating out some of the incoming IR from the sun. These molecules are just as likely to cool us as warm us." as an argument). It's nice that wikipedia gives these folks a forum. Gzuckier 16:26, 5 March 2007 (UTC)

First of all, if you think the sun doesn't send IR our way, maybe you should review basic science. Second, the atmosphere is not transparent to the visible spectrum. Have you ever seen a cloud? Finally, variations in carbon mearsurements are taken into account. That's why several models are compared and ALL models indicate higher levels of atmospheric carbon dioxide between 400 and 500 million years ago. During which time the earth experienced the harshest ice age of the past half billion years. If you want to tell me that our dating methods are off by more than 100 million years, then you belong to the ranks that believe evolution is fiction and the earth is only thousands of years old. 132.5.72.9 18:31, 5 March 2007 (UTC)

The earth does receive IR from the sun; in fact, about half of solar radiation is in the near-IR. But the relevant physics are totally different than for the longer-wavelength IR emitted by the earth, and there's so little overlap in the wavelengths of solar and terrestrial radiation that they need to be considered as two completely different streams. Raymond Arritt 18:54, 5 March 2007 (UTC)

TEMPERATURE (Kelvin)	740 to (3,000-5,200)	(92.5-140) to 740	(10.6-18.5) to (92.5-140)
WAVELENGTH (microns)	(0.7-1) to 5	5 to (25-40)	(25-40) to (200-350)
SPECTRAL REGION	Near-Infrared	Mid-Infrared	Far-Infrared
Gzuckier 18:07, 6 March 2007 (UTC)

Water vapor has several absorption bands in both streams. It doesn't send temperatures in one direction. Instead the greenhouse gas keeps temperature balanced. Cloud cover has a net cooling effect, so even if our minuscule contribution of carbon dioxide brought temperatures up, increased water vapor and cloud cover would balance it out. 132.5.72.9 17:27, 6 March 2007 (UTC)

Look, if you're trying to convince us you're an expert, it's not working. Gzuckier 18:07, 6 March 2007 (UTC)

No, you're wrong. Anon is an expert is the special branch of science where all effects are equal and opposite, regardless of mechanism, and all equations are written with binary coefficients. The technical translation of "would balance out" is "has opposite sign". Since the only coefficients in the system are +1, 0, and -1 any pair of numbers with opposite sign cancel to zero. MaxEnt 18:43, 8 April 2007 (UTC)

Technically, those would be Balanced ternary coefficients. --njh 19:25, 9 April 2007 (UTC)

Can I suggest...

Can I suggest that the following sentence (in "Anthropogenic greenhouse effect"):

"Because it is a greenhouse gas, elevated CO2 levels will increase global mean temperature"

is an uncorroborated assertion, i.e. a mere opinion without basis. The reference to the Science article refers to a correlation between rising temperatures and increases in CO2 levels. This does not equate with causation. Pearcedh 19:46, 9 March 2007 (UTC)

Not really. But the text around it could do with some changes William M. Connolley 20:51, 9 March 2007 (UTC)

as it stands, this statement "Because it is a greenhouse gas, elevated CO2 levels will increase global mean temperature" IS a theory. therefore why is the first users edit so bluntly denied?

I agree totally with Pearcedh´s statement. This becomes more evident when we know that IPCC correlates the increase of CO2 from 1960 to ~2000 isolately with the increase in temperature of that period, but just in that same period the cloudiness also increased (see this at http://noparadoxes.tripod.com). —Preceding unsigned comment added by 189.10.214.45 (talk) 22:46, 29 November 2007 (UTC)

This is no more of an unfounded assertion than that photons carry the electromagnetic force. It's based on the best science we have—and there are plenty of reliable sources to support it. Ben Hocking ^{(talk|contribs)} 23:31, 29 November 2007 (UTC)

The student Ben Hocking´s (seems to enjoy fighting as in the hockey games) argumentation has no fundament. There is nothing to do his statement with the historical increase in temperatures, which cause even the IPCC cannot prove that the CO2 is the unique responsible for.

Of course not, since (a) there is no proof in science, and (b) we all know that CO2 isn't the unique cause. You have actually read - or at least skimmed - the IPCC reports that you presume to disagree with, haven't you? William M. Connolley 23:27, 30 November 2007 (UTC)

(a) In true science there are lots of proofs, however not in empiricist science. So, as you think that in such science there are no proofs, how do you defend the "exact" IPCC´s soothsayings for a time 100 years (!) ahead?? Don´t you think that the true science do not allow such previews?

In the article http://noparadoxes.tripod.com there are lots of scientific proofs.

After glancing over that web article I have little response to add, although I wish to state that I have no comment. Raymond Arritt (talk) 20:55, 6 January 2008 (UTC)

First paragraph

The greenhouse effect, discovered by Joseph Fourier in 1824 and first investigated quantitatively by Svante Arrhenius in 1896, is the process in which the emission of infrared radiation by an atmosphere that warms a planet's surface.

There is a grammar error here. Two brownies and a gold star for the first successful fix! --Uncle Ed 17:04, 21 March 2007 (UTC)

Sandbox proposal

A sandbox for contributors to try out different introductions to the article is here:

• /intro

Note that this is not intended as a "branch" but as a showcase for various competing versions. The 3RR does not apply to it, because it is a sandbox.

When a sandbox version gains consensus, it can replace the current intro. --Uncle Ed 17:09, 21 March 2007 (UTC)

Greenhouse_effect#Real_greenhouses

To altitude 11km is the temprature not determineted per radiation, but the convection. The the absorbed radiation reduced the convection heat flux, but not change the temperature. Over 11 km ist the temperature determined be radiation balance. Excuse me my english. --217.82.191.244 12:12, 17 May 2007 (UTC)

Reflected light

The Earth receives energy from the Sun in the form of radiation.
The Earth reflects about 30% of the incident solar flux;

I'm wondering, what becomes the radiation which has been reflected from Earth to Universe? Does it just lights out the planet or something? Or can it be re-used for hem... other purposes? (it's only a curious question, but the curious are never answered... if you know the answer, spend time for humanity and free encyclopedia and such... and click edit button to answer me) 194.199.142.126 14:43, 25 May 2007 (UTC)

Main article - global warming?

Global warming is certainly not a main article of greenhouse gases.. WinterSpw 05:56, 12 June 2007 (UTC)

Agreed William M. Connolley 08:23, 12 June 2007 (UTC)

We need some more feedback here. WinterSpw 04:22, 15 June 2007 (UTC)

"greenhouse gases" section needs a rewrite

I'm not too jazzed about this explanation of how the greenhouse gases absorb IR light, especially the part about the "floppier" molecules contributing more. Then again, I'm not sure how intelligible everyone wants this article to be to the layperson. (I'll get technical for a second and then move on to my point) Just so we're all clear, the criterion for absorption of IR light by a molecule is that the dipole derivative of the vibrational mode to be excited in that molecule is nonzero (at least within the dipole approximation). "Floppier" has little to do with it: carbon monoxide, if it were present in large quantities (and thank God it's not), would be an important contributor to the greenhouse effect as well, because stretching the C-O bond changes the dipole moment of the molecule (nonzero dipole derivative). And CO is probably one of the least "floppy" molecules around.

Okay, technical stuff over. If we want the article to be technical, this stuff should certainly be in there. I was under the impression, however, that the article should be at least somewhat accessible to the layperson with a passing interest in science. In that case, maybe it would be more conceptually efficacious to throw in a little graphic of a molecule vibrating, with maybe an arrow or something representing the dipole changing over the course of a vibrational period. This would be especially effective with CO2: showing the symmetric and asymmetric stretches side-by-side and illustrating that the asymmetric case is the one for which the dipole changes and hence is IR-active, whereas the symmetric stretch is not.

Anyway, just a suggestion.

PS--I also realize that larger molecules do have more vibrational modes and would also contribute appreciably to the greenhouse effect were they present in the atmosphere in any significant quantity. I'm just concerned that the layperson would read this and misunderstand the mechanism at work here. Sorry, I'm a spectroscopist--it's my bread and butter.

I suggest you have a go - make it technically correct but still readable William M. Connolley 08:22, 14 June 2007 (UTC)

Interesting article

I recently came across an interesting article and a possible source to be used for this article in the 1955 Monthy Weather Review. — jdorje (talk) 04:41, 31 August 2007 (UTC)

You're right, it is indeed interesting, from a historical point of view William M. Connolley 08:54, 31 August 2007 (UTC)

Have the laws of physics relevant to climate science changed significantly since 1955?Gordon Vigurs 07:02, 11 September 2007 (UTC)

An odd question. Did you read the article? The answer is, no, obviously not; but we now have the Mauna Loa record of CO2, and measurements from ice cores William M. Connolley 08:24, 11 September 2007 (UTC)

Would an article on 'timeline of greenhouse effect knowledge' be a good idea? Sounds like a useful reference to me to allow answers of the 'but this is well established for xx years' type. It probably wouldn't work out that way as lots of information slowly gets firmed up over many papers and including them all wouldn't be reasonable. crandles 10:53, 11 September 2007 (UTC)

Sorry, just a bit of unseemly sarcasm, please feel free to delete. This article is very important, but insufficient to inform the layman of the most important issue - how accurate are the predictions? Few people are impressed with systems which only predict past events. And the brow-beating style of some of the above comments give the impression of Emperor's New Clothes. Could we have, for example, the mean temperature for July 2010 in London, corresponding to a range of different environmental policies, to demonstrate that current models can indeed predict future events.Gordon Vigurs 12:41, 12 September 2007 (UTC)

The article isn't about predictions. You want global warming for that. July 2010 is weather, not climate William M. Connolley 13:56, 12 September 2007 (UTC)

Nevertheless (although William is correct that this is off-topic), here are two articles that deal with predictions: [2] [3]Ben Hocking ^{(talk|contribs)} 14:00, 12 September 2007 (UTC)

All legitimate science is about predictions. The theory which fails to predict future events is discarded as false, or demonstrated to be a special case of a more general theory. If it is not about prediction, it is not about science. In view of the infallibility clained for current climate modeling, it appears reasonable to expect precise predictions, with identifiede error bounds.Gordon Vigurs 07:48, 16 September 2007 (UTC)

You're still on the wrong page guv. The predictive elements of GHE and/or climate modelling are... where you've been pointed to. The stuff here is a part of radiative physics, which does indeed make well tested predictions. You're wrong that all science must make predictions, unless you want observational astronomy or ecology to be non-science; something the Popperians might do I suppose. Oh, and "infallibility" is silly, of course William M. Connolley 08:43, 16 September 2007 (UTC)

Parasol Effect

The processes of global warming presented are incomplete. The effect of atmospheric aerosols and dust cannot be ignored. Gordon Vigurs 10:41, 6 September 2007 (UTC)

In describing the earths climate, no. In describing the GHE, yes. You may want global warming or global dimming William M. Connolley 10:47, 6 September 2007 (UTC)

Thanks - these are both interesting articles Gordon Vigurs 10:52, 6 September 2007 (UTC)

Radiation Diagram

Can anyone confirm that the diagram at the top of this article really represents the Greenhouse Effect? If it does then I think that at the very least this represents a major breach of the 2nd law of thermodynamics. There is no doubt that, on a global scale, the lapse rate ensures that the troposphere is cooler than the surface, how then is this cooler troposphere able to radiate 324W/m2 to the surface? When this reaches the surface it is absorbed 100%, not possible! If there is something I have missed then please tell me, but the science of thermodynamics describes heat transfer and this diagram appears to drive a coach and horses through the 2nd law. I propose to place a statement to this effect at the top of the article in a prominent position, a sort of smoking warning! Damorbel 15:51, 16 September 2007 (UTC)

324 atmosphere to earth is less than 452 from earth to atmosphere. That is the way round I would expect. The atmosphere shows 519 in and out also as I would expect. Of 519, 324 goes to earth and 195 to space. Obviously this is not showing heat transfers within the atmosphere so you 100% doesn't seem to be a problem to me. crandles 17:11, 16 September 2007 (UTC)

In my opinion, there are many problems with that image - but, if you know those limitations the image can still be very useful. As for the planet absorbing 100% of the energy from the atmosphere, I think we have to assume that the atmosphere is actually radiating more than indicated but that only 324W/m2 are actually absorbed. What I find interesting is that more heat is shown coming from the atmosphere than from the sun.

As for the lapse rate, that's one of the problems with images of this type. I would prefer an image that shows the contributions of various parts of the atmosphere. For instance, using the "Earth standard" lapse rate of 6.5°C/km, a temperature drop of 33°C (the temperature increase produced by the Green House effect) represents only 5km (~16,000ft). Since 11km (~36,000ft) is usually considered the top of the troposphere and because the troposphere is heated primarily by convection, not radiation, it would be useful if the image showed convection and radiation effects separately instead of lumping them together.

I have a related question - The article says

The Earth reflects about 30% of the incoming solar radiation. The remaining 70% is absorbed

But the image caption says (click on the image to see this)

Direct overhead sunlight at the top of the atmosphere provides 1366 W/m2; however, geometric effects and reflective surfaces limit the light which is absorbed at the typical location to an annual average of ~235 W/m2.

Well ... 235/1366 indicates (to me) that only about 17% is absorbed, not 70%. Can someone please explain this? Q Science 02:40, 17 September 2007 (UTC)

The 1366 W/m2 value is for a beam perpendicular to the earth (it's typically called the "solar constant", though it isn't precisely constant). At latitudes above the equator the beam won't be perpendicular, and on the dark side of the earth the beam won't be there at all. Quantitatively, we account for this by scaling the solar constant by the ratio of the area of a disk to the surface area of a sphere. The area of a disk is pi*r^2 while the surface area of a sphere is 4*pi*r^2, so the ratio is simply 1/4. Multiply 1366 W/m2 by 1/4 to get the mean irradiance over the earth; this works out to 341 W/m2. Now multiply this by 0.7 to get the fraction that is absorbed and you end up with 239 W/m2 which is essentially the stated value of 235 W/m2. I just gave away the answer to a classic homework problem, but what the heck... Raymond Arritt 02:51, 17 September 2007 (UTC)

Thanks - I suggest adding that to the image description on Image:Greenhouse Effect.png Q Science 03:43, 17 September 2007 (UTC)

Solar Spectrum Image not Displaying at 350px

The image Solar Spectrum.png is not displaying in my IE browser when the size is given as 350px. It does display with a size of 400px and 500px. Note that the image size is actually 800×595. I don't know if it is just my system or a more general problem.

Image:Solar Spectrum.png|thumb|350px|right|text here ....

• Pages with 350px - Greenhouse effect Solar variation
• Pages with 400px - Solar radiation
• Pages with 500px - Sunlight

I did try editing the tag, and the size was the only thing I had to change to see the image. Currently, on both 350px pages, all I see is a white box and the caption. Q Science 16:28, 17 September 2007 (UTC)

I checked all 4 pages with IE on two other machines and they all display correctly. Is it just my system, or are others having the same problem? Q Science 19:15, 17 September 2007 (UTC)

Removing gasses table source

If Water vapour: feedback or forcing? is going to be used as a reference, then that should be said as the source. So I made everything match what the reference says. While I don't doubt that Dr. Connolley's knowledge of what's in Ramanathan and Coakley (1978) the reference is not to it.

If the reference is changed to the paper, Ramanathan, V. and J. A. Coakley, Jr., 1978: Climate Modeling through Radiative-Convective Models. Rev. Geophys. and Space Physics, 16: 465-490. http://www-ramanathan.ucsd.edu/publications/Ramanathan%20and%20Coakley%20RevGSP%201978.pdf that's fine too. (Sorry if I did that backwards, I didn't find the actual paper before I changed the article.)

In any case, it all matches now, number, source, reference.

Actually, the reference says

CO2 alone makes up between 9 and 26%

so the 12% (that you removed) was kind of an average. Q Science 17:57, 25 October 2007 (UTC)

I'd also like to see Clouds and Other GHG added to the table, but I don't know if that's needed. Sln3412 21:26, 24 October 2007 (UTC)

No, CO₂ alone absorbs 26% (IPCC 25%) of the total. The reference shows that with RC78, removing CO₂ leaves the GE -12%, while the 2005 ModelE leaves the GE at -9%. CO₂ is 25/26 if it's the only component left, not the only one removed.

So they are two different things; no CO₂ is 9%/12%, CO₂ by itself is 25%/26%. The chart shows two different situations, removing something from the whole versus using one thing alone.

As another example, the chart at Real Climate shows removing O₃ absorbs 3%, but O₃ as the only factor absorbs 7%.

It's like asking if there's 10 apples, and you take 3, 'how many are left' or 'how many do you have'. They don't mix, the first question's answer is 7 and the second 3; you can't put the two questions together and get the answer of 5 using the median or mean of 7 and 3. Sln3412 20:09, 26 October 2007 (UTC)

Thanks for the clarification. I would have never gotten that without a little help. The text in the reference (quoted above) did not suggest that interpretation. I suggest also changing removal of both of these constituents will be greater than 45% to will be 47% to be less ambiguous. Q Science 05:05, 27 October 2007 (UTC)

Celsius-Fahrenheit confusion

Due to the recent confusion identified on RealClimate[4], I added the Fahrenheit conversions in the introductory paragraph, which will allow the Celsius-challenged to read this article without puzzlement. I hope this is fine with the rest of you. Iceberg007 03:53, 13 November 2007 (UTC)

Good idea. Raymond Arritt 03:58, 13 November 2007 (UTC)

So was this [5] William M. Connolley 16:10, 13 November 2007 (UTC)

I agree! :P Iceberg007 21:22, 13 November 2007 (UTC)

Uhh am i missing something or do both temperatures show 59'F?

33C is 91.4F —Preceding unsigned comment added by 91.105.43.151 (talk) 17:43, 13 March 2008 (UTC)

Vandalism

Woo, lots of kiddos with spray cans today on this one. Cheers for those who beat it down better than I =) Ryo 18:47, 13 November 2007 (UTC)

Experimental Evidence

There are innumerable theoretical calculations and climate models that either allude to or rely upon the greenhouse effect. However, in all of these there does not appear to be any reference to experimental confirmation of the theory. I know that there has been voluminous discussion about real greenhouses and the greenhouse effect but is there a defining experiment that confirms the theory? If so, should it not be at least referenced in the article? —Preceding unsigned comment added by 69.244.42.213 (talk) 18:54, 29 January 2008 (UTC)

Depends what you're looking for. Obviously, we won't get to test what a planet otherwise like earth but with no GHG, or no CO2, in the atmosphere behaves like. There is any amount of basic radiative physics that the GCMs use to build their radiative codes; I've never read that stuff and anyway I doubt it would be very useful here William M. Connolley (talk) 20:53, 29 January 2008 (UTC)

I'm looking for something like the experimental verification of, say, Planck's law or the Stefan Boltzmann law where the theory predicts the outcome of an experiment. Is there such a laboratory experiment? I can think of a general scheme where two strong transparent canisters, one containing CO₂ and the other containing N₂, are suspended on a fine string inside a vacuum chamber and illuminated with a heat lamp while measuring the temperature over time. Has something like this not been done? —Preceding unsigned comment added by 69.244.42.213 (talk) 20:43, 30 January 2008 (UTC)

Not quite what you want, but http://www.wmconnolley.org.uk/sci/wood_rw.1909.html is somewhat relevant. At the level of basic level of radiative physics, the experiment you describe would be pointless, because the results are known. It might be done at high school or by undergrads just to demo theory, but it wouldn't be done as publishable science, at least not nowadays. I'll point a radiative friend at this page and see if he has anything to say William M. Connolley (talk) 20:51, 30 January 2008 (UTC)

The greenhouse effect is an issue of radiative energy transfer as William said. A useful place to look would be if we can model emissions from the earth as observed in space. Take a look at http://www.sp.ph.ic.ac.uk/~gerb/gerbteam/GERBProject_JEHarries_BAMS_revised.pdf

This is more on point but it is behind a paywall http://adsabs.harvard.edu/abs/2001Natur.410..355H

There are other place, but that seems the best to answer your questions. Much of the work was done based on measurements from the ATMOS instrument that was flown on Skylab and the first shuttle missions.

Combining a radiation transfer code like FASCODE or MODTRAN with a GCM or a weather model and out pops the greenhouse effect. Things are not perfect (for one thing the number of levels in the models is pretty low) but they are good enough to answer your question positively. —Preceding unsigned comment added by Jhalpern (talk • contribs) 03:04, 31 January 2008 (UTC)

Hmm...I guess if you want something done...I'll set up that high school experiment and see what I get. By the way, since we know what the results will be, what will the results be? —Preceding unsigned comment added by 69.244.42.213 (talk) 14:54, 31 January 2008 (UTC)

Not very much interesting because you can't isolate the gas from the walls, which will exchange energy by radiation and conduction. —Preceding unsigned comment added by 138.238.33.67 (talk) 18:17, 31 January 2008 (UTC)

If you shine IR through two gases, one of which absorbs IR and the other doesn't, then the one that absorbs IR will get warmer. Exactly how much depends on how strong the IR is, how thick the gas is, and how fast it loses the energy William M. Connolley (talk) 20:32, 31 January 2008 (UTC)

By doing the experiment in a vacuum chamber, the conduction/convection should be essentially eliminated. Radiation from the walls of a container should not have a greater effect than radiation from non-greenhouse gases in a planets atmosphere. It would not be a viable experiment if one used an IR laser tuned to the absorption line of the greenhouse gas. I will need to use a blackbody source (heat lamp) to get something that can represent the system of interest, i.e., a planet's atmosphere under solar illumination.

I was looking for something a little more quantitative, William. Perhaps my question was too vague. :) —Preceding unsigned comment added by 69.244.42.213 (talk) 15:55, 1 February 2008 (UTC)

The infrared source (emitter) creates a high-intensity stream of energy incorporating all wavelengths in the infrared spectrum.

The stream passes through the optical filter, which blocks all wavelengths except those that CO2 absorbs. The filtered infrared energy strikes the detector and causes it to heat up. When CO2 is drawn through the sampling cell by the D-TEK CO2’s internal pump, some of the infrared energy is absorbed by the CO2. This causes a decrease in the amount of infrared energy reaching the detector and a corresponding drop in the detector’s temperature, which triggers the D-TEK CO2 to alarm. This whole process takes a fraction of a second.

By utilizing an optical filter with precise characteristics, INFICON has made D-TEK CO2 sensitive to CO2 while minimizing false alarms. In addition, the detector recovery time is also immediate after the CO2 clears the cell.

http://www.inficon.com/download/en/D-TEK_CO2.pdfGzuckier (talk) 16:38, 1 February 2008 (UTC)

Wikiproject Earth

Hello i have recently proposed the Wikiproject Earth. This Wikiproject`s scope includes this article. This wikiproject will overview the continents, oceans, atsmophere and global warming Please Voice your opinion by clicking anywhere on this comment except for my name. --Iwilleditu^{Talk :)Contributions} —Preceding comment was added at 15:37, 30 March 2008 (UTC)

Reason being

the reason for these greenhouse gasses is the uneven heating of the earths serface —Preceding unsigned comment added by 24.46.165.19 (talk) 23:14, 31 March 2008 (UTC)

Faint young Sun problem has been solved

See here

Warming the early Earth - CO2 reconsidered

Authors: P. von Paris (DLR), H. Rauer (DLR, TUB), L. Grenfell (DLR, TUB), B. Patzer (TUB), P. Hedelt (DLR), B. Stracke (DLR), T. Trautmann (DLR), F. Schreier (DLR) (Submitted on 25 Apr 2008) Abstract: Despite a fainter Sun, the surface of the early Earth was mostly ice-free. Proposed solutions to this so-called "faint young Sun problem" have usually involved higher amounts of greenhouse gases than present in the modern-day atmosphere. However, geological evidence seemed to indicate that the atmospheric CO2 concentrations during the Archaean and Proterozoic were far too low to keep the surface from freezing. With a radiative-convective model including new, updated thermal absorption coefficients, we found that the amount of CO2 necessary to obtain 273 K at the surface is reduced up to an order of magnitude compared to previous studies. For the late Archaean and early Proterozoic period of the Earth, we calculate that CO2 partial pressures of only about 2.9 mb are required to keep its surface from freezing which is compatible with the amount inferred from sediment studies. This conclusion was not significantly changed when we varied model parameters such as relative humidity or surface albedo, obtaining CO2 partial pressures for the late Archaean between 1.5 and 5.5 mb. Thus, the contradiction between sediment data and model results disappears. Comments: 55 pages, 4 tables, 11 figures, accepted in Planetary and Space Science Subjects: Astrophysics (astro-ph) DOI: 10.1016/j.pss.2008.04.008 Cite as: arXiv:0804.4134v1 [astro-ph]

Count Iblis (talk) 00:48, 29 April 2008 (UTC)

25°C vs. 30°C

I saw some edits, and someone claimed that without green gases, Earth's surface would be "25°C" cooler; while the other claimed that person was speculating or something like that. How is possible to know which one is right and wrong? --Gh87 11:54, 2 November 2006 (UTC)

Remove the atmosphere and it is a simple blackbody calculation. T = ((1-albedo)*solar flux/(5.67*10^-8 W/m²/K⁴)^1/4. Solar flux is 342 W/m² at the top of the atmosphere, so it reduces to 278.6 K * (1-albedo)^(1/4). Where modern average temperature is 287 K. The question comes in, what does one assume for the albedo. Current global albedo, with clouds, is about 0.3. Albedo of the modern surface, neglecting the atmosphere, is about 0.15. However, if you remove the greenhouse effect, the whole globe will quickly freeze solid and the albedo of that snow and ice covering could be 0.6-0.8.

So depending on what you want to assume:

• albedo = 0.15: 20 degrees C
• 0.3: 33 degrees C
• 0.6: 66 degrees C
• 0.8: 100 degrees C

~30 degrees is what is normally given, but that assumes rather nonsensically that you can remove the entire greenhouse effect while having no effect on cloud cover or any other aspect of the Earth's albedo. So I guess take your pick on what you want to say about what happens when you "turn off" the greenhouse effect. Dragons flight 13:05, 2 November 2006 (UTC)

Is there something missing from this temperature calculation? What about the heat inside the earth which is constantly being transmitted from the hot interior to the surface? What is the magnitude of this geothermal heat transfer? Shouldn't the effect of this be added to the solar flux effect to calculate a non-greenhouse temperature? Penurious (talk) 17:34, 28 April 2008 (UTC)

Conduction of heat from the Earth's interior is well below 0.1 W/m2, and makes a difference of only about 0.01 K in temperature. Raymond Arritt (talk) 17:42, 28 April 2008 (UTC)

This leads to a quatitative argument against a large significance for anthropogenic global warming. Pls debunk the following. Penurious (talk) 15:47, 8 May 2008 (UTC)

 Entire current greenhouse effect of atmosphere: 30 degrees C
 Estimated CO2 fraction of greenhouse effect: 10% or 3.0 degrees
 Estimated increase in CO2 effect for doubling of CO2: 5%
 Resulting temerature increase from maximum possible
   anthropogenic greenhouse effect: 0.05*3.0 == 0.15 degrees.

I really don't have a clue about this, but could it be that they meant 10% + 5% so that would mean 0.15*30 = 4,5 °C, an increase of 1.5 degrees.
— Apis (talk) 16:14, 8 May 2008 (UTC)

Here's a crazy idea: Instead of doing our own back-of-the-envelope calculations, maybe we could cite the results of calculations from the academic literature. Just a thought. Raymond Arritt (talk) 16:36, 8 May 2008 (UTC)

I strongly disagree, it's much more fun to make things up as we go along. ;)
— Apis (talk) 20:41, 8 May 2008 (UTC)

I humbly ask the experts for citations and reasoning to refute this. I'm not against citations.

Here are citations supporting the above numbers: the 30 degrees are from this section of talk on the greenhouse_effect article. The 5% increase in CO2 effect comes from http://www.john-daly.com/forcing/moderr.htm in the section 3 on radiative forcing. He mentions an increase of downward radiation of 3.7 W/M**2 out of 74 W/M**2 for CO2 doubling. The 10% CO2 effect I get from the greenhouse_effect article. Penurious (talk) 21:13, 8 May 2008 (UTC)

Daly is (a) dead and (b) incompetent. I'm not going to bother wasting time discussing his fantasies. If you want to, usenet beckons. Don't waste our time here William M. Connolley (talk) 21:29, 8 May 2008 (UTC)

Well, I don't think there's anything wrong with asking questions, but this is the wrong forum for it. :) This page is for discussing how to improve the article not the topic itself.
— Apis (talk) 21:43, 8 May 2008 (UTC)

Radiation transmitted by atmosphere

The absence of scales, or indeed a clear indication of what property of the atmospheric gases is being presented, renders this diagram confusing. Presumably the most relevant region is around 12 microns, corresponding roughly to the black body temperature of 288K, but 8-13microns is an atmospheric window, which why it is widely used by thermal imagers. The diagram of atmospheric absorption correctly shows that neither CO2 nor water vapour have much effect here, CO2 appears to absorb in the 12-20 micron region, whilst water vapour appears to absorb both above and below this region. Since there are no scales on the vertical axis it is difficult to conclude anything from this diagram. If these are extinction coefficients for the gases, then the diagram would indicate that water vapour would have a much greater effect than CO2, if they represent the proportion of absorption due to typical atmospheric concentrations of the two gases, then the effect of CO2 is spectacularly greater than that of water vapour. Could somebody please clarify this.

As presented, it would appear that as the surface temperature increases, the amount of energy in the CO2 absorption band reduces, whilst that in the water vapout absorption band increases, implying that water vapour becomes the more important greenhouse gas, which I suspect is not the case.Gordon Vigurs 20:48, 7 September 2007 (UTC)

Water vapor is already (by a large margin) the most significant contributor to the natural greenhouse effect. 76.231.189.193 18:05, 8 September 2007 (UTC)

You are correct, the graph is very misleading - as the surface temperature increases, the amount of energy in the CO2 absorption band also increases. But not as much as the energy in other bands.

The reason the Sun has no energy in that band is simply because it is a long way away ... and the graph shows the energy at the top of the atmosphere. Q Science 07:27, 15 September 2007 (UTC)

Mentioning of greenhouse effect on Venus is even more confusing. A surface temperature of about 450K corresponds to peak emission at about 6microns, where CO2 does not appear to have much effect. How then can this effect be attributable to the high CO2 concentration in the Venusian atmosphere?

Also the 'Rayleigh scattering' term. What particulate or droplet size is assumed? Is this some kind of average? If Rayleigh scattering is only significant below 1 micron, how can weather radar, operating typically at millimetric wavelengths, possibly work? Gordon Vigurs 17:55, 9 September 2007 (UTC)

The weather radar article gives a good explanation. Rayleigh scattering depends on the ratio of the wavelength to the particle size, not on the absolute value of either. Raymond Arritt 19:31, 9 September 2007 (UTC)

True, and the reason for my request for information regarding particulate size, but irrelevant to my criticism of this diagram, which is attenuation as a function of absolute wavelength. It shows no attenuation at microwave frequencies.Gordon Vigurs 06:49, 10 September 2007 (UTC)

On another note:

What is the chage in CO2 emission to outer space with respect to CO2 concentration. Why is change in absorbtion by CO2 discussed but change in emission is not? All things being equal, if we add CO2 to the atmosphere there will be a resulting increase in radiation absorption AND there will also be a resulting change in re-emission into outer space which offsets the absorption. Does emission increase or decrease as a function of CO2 concentration? If it increases, is its change less than the change in absorption? If not, ineasing CO2 concentration will tend to cool rather than heat the atmosphere. We know that greenhouse gas emission to outer space sometimes increases as a function of gas concentration: otherwise re-emission to outer space would now be zero. Why is this never discussed? Penurious (talk) 17:27, 28 April 2008 (UTC)

The atmosphere gets heated by the radiation from the earth. So the atmospere heats up and thus will also emit radiation. However, the atmosphere emits it's radiation in all directions, both up into space, and down towards the earth. So (this is the important part) half of the radiation emitted by the atmosphere is going down, back to the earth, again. So in effect the CO2 in the atmosphere works as a insulating blanket. If you double the amount of CO2 you basically add another blanket. This is a pretty crude simplification, but hopefully it can convince you that adding more CO2 would not cool down the earth. :) Apis (talk) 20:13, 28 April 2008 (UTC)

Let me try to explain again by going into gory detail. Peter Deitz at http://www.john-daly.com/forcing/moderr.htm demonstrates how in the IPCC TAR the change in global temperature "best guess" for doubleing of CO2 has been calculated using differential form of the Stefan-Boltzman law S = εσT**4, which he states as being:

                    dT/T = 1/4*dS/S
                    S is heat flow in watts/M**2
                    T is temperature in Kelvin
                    σ is a physical constant 5.6704*10e-8
                    ε is emissivity, a value between zero and 1.0

The technique is starts with assuming some dS=4.3w/m**2 (his reduced value) as a result of CO2 doubling and using S=240 w/m**2 and T=255K as typical values at the tropopause level we can come up with a dT of some 1.14K degrees of global warming (less than IPCC's).

The differential form is arrived at by taking the derivitive of S = εσT**4 with respect to T and dividing by the original equation.

                    dS    =    4εσT**3
                    ---        -------  
                    S           εσT**4

However this assumes that emissivity does not change along with temperature when CO2 is doubled. (This is my big issue here). If it does, we have to use the partial differential form of Stefan-Boltzman which is

                    dT/T = 1/4(*dS/S-dε/ε)

From this we see that if emissivity changes when CO2 doubling happens, temperature increase is lessened or even reversed. In fact it would take only a 2.0% change in emissivity to wipe out all the effect of the increased flow of watts into the atmosphere from CO2 doubling. Why would emissivity change? Because there are 2X as many CO2 molecules and each one is a heat transmitter as much as it is a receiver.

So besides capturing heat, greenhouse gases also cause the atmosphere to be able to cool off. Could it be that with the current state of CO2 saturation in the atmosphere, that point has been reached and passed where we are only cooling the atmosphere by adding CO2?Penurious (talk) 04:42, 29 April 2008 (UTC)

Agreed: increasing GHG's increase emission too. And there is a balance between this and more absorption. In broad terms, it is easy to see that going from no GHG to some GHG results in warming at the sfc. What happens in a real atmosphere with increments to GHGs is far more complex and needs a model William M. Connolley (talk) 07:26, 29 April 2008 (UTC)

Im a bit confused =S emissivity might change a bit with temperature, but if they considered it constant, I assume it probably is relatively constant in the temperature ranges involved (is there reason to believe it isn't?). I'm not convinced that emissivity of the gas would change because you double the amount of molecules though? And I would think that the energy emitted from earth to space match the energy of the sunlight absorbed due to equilibrium (i.e. with 30% reflection that would be about 0.7 * 1370 W/m² * πR²). The GHG in the atmosphere would affect the surface temperature but not the amount of energy emitted back into space? Maybe I'm missing the point, I'm certainly not qualified to judge if there is a mistake in one of the IPCC reports =) Maybe someone else can give a better answer, there are probably some expert around. Apis (talk) 15:06, 29 April 2008 (UTC)

Why does emissivity of the gas change when GHG is added? Because when more greenhouse gas is added the absorption of radiation is increased. This is the supposed basis of greenhouse effect. However according to Kirchhoff's law, the emissivity must equal the absorption; so emissivity increases also by the same amount. Isn't this just basic physics? All these discussions seem to ignore this.Penurious (talk) 13:31, 30 April 2008 (UTC)

Yes, ok, emissivity as far as I know is the ratio of absorption/emission compared to an ideal blackbody. So the emissivity for the gas mixture (atmosphere) would change if you add more co2. But the warming caused by the greenhouse gases is because ca 50% of the absorbed radiation (emitted from earth) is being re-emitted down towards earth again, thus the surface will end up at a higher temperature at equilibrium (the other 50% goes out into space). Adding more ghg gases would increase absorption, but 50% of what is absorbed will still be bounced back again, since that is now more radiation than before, the resulting temperature at the surface will be higher than before. The amount of radiation absorbed from the sun and re-emitted into space will be the same as long as there is an equilibrium (otherwise earths temperature would keep rising/falling). This assumes the atmosphere is a single layer, if you model it as many layers you would have to consider the radiation going back and forth between each. --Apis (talk) 14:44, 30 April 2008 (UTC)

Hope this makes sense, at least that's what I have learned. =) Apis (talk) 16:56, 30 April 2008 (UTC)

If your doubts are at that level, then you might find the basic analytically-solvable version helpful. Start with a black body with no atmos illuminated by SW radiation S. Work out its sfc T. Then add in a layer of "atmos" which is transparent to SW but grey, ie of emissivity e (0<=e<=1) in the LW (assume that the planet absorbs all SW and re-emits it as LW proportional to T^4. Then vary e and see what happens. You will find that sfc T depends on e (increases with e) William M. Connolley (talk) 22:15, 30 April 2008 (UTC)

OK I get it: increased GHG causes increase emission of LW radiation from the atmosphere to earth thus rasing the sfc T surface temperature of the earth. In a manner of speaking, the greenhouse effect of the atmosphere is to partially reflect LW radiation back to earth increasing its radiation input. Ulitimately with perfect GHG saturation (100% absorption of LW), the earth would aquire an equal amount of SW (sun) and LW (atmosphere) radiation input. Would you then say that Kirchhoff's law dictates that with respect to an element of atmosphere, the change in GHG alone (without change in radiation input) cannot change the temperature since emissivity always == absorptivity? And likewise would it be true that, considering radiation effects alone, the atmosphere can't heat up unless the sfc T of the earth does first? Penurious (talk) 15:49, 8 May 2008 (UTC)

Not perfectly sure what your question is. If we assume that the atmos is transparent to SW but grey in the LW, and that solar has no LW, then the radiation that warms the atmos comes from the planet. If the planet gets warmer, or the atmos gets more opaque, it warms. I'm not sure what you are saying re K. If e=1 in the simple one-level model, then adding more GHG makes no difference. If e<1, then increasing e warms the atmos if the solar radiation remains constant.

Its easiest to see this with a toy model. Assume we have solar radiation at S1=(1-a)S/4 per sq m (S/4 cos of the area of a sphere vs cross section, "a" is the albedo). Assume the planet radiates LW at rT^4. Assume a layer of atmos of temp U transparent to SW and of emissivity 0<=e<=1. Then the radiaton downwards at the sfc is S1 + erU^4. The radiation up is rT^4; hence rT^4=S1+erU^4. The radiative balance of the layer gives you 2erU^4=erT^4 hence 2U^4=T^4. Hence T^4=S1/(r(1-e/2)) if I haven't got my numbers wrong. Draw a picture, it will make more sense William M. Connolley (talk) 19:26, 1 May 2008 (UTC)

To a reasonable first approximation, radiative heating/cooling at a given height in the atmosphere depends on the rate of change of emissivity with height and the rate of change of temperature with height. I'm not aware of any really easy way to explain this, but you can get some insight by drawing a cartoon of a simplified atmosphere with only two layers. Raymond Arritt (talk) 15:36, 29 April 2008 (UTC)

Pure radiative and convective-radiative model

I don't understand the relationship between the pure radiative model (RM) and the radiative convective model (RCM). In the RCM the greenhouse warming effect seems to be dependent on the temperature decreasing with altitude. Let's assume the temperature was constant throughout the atmosphere. In that case while I can see why the altitude of IR emmisions to space would increase with more greenhouse gases it would seem that there would be no need for the temperature to increase to maintain the balance with incoming solar radiation.
On the other hand in the RM it seems to me that the altitude at which IR emmisions reach space is also going to increase with increasing greenhouse gases. Surely the IR opaqueness is a purely radiative property? And if this altitude increases then the surface temperature won't need to increase to balance incoming solar radiation.
I suppose my point is that in the article the RCM differs from the RM in two respects: (1) decreasing temperature with altitude and (2) IR opacity leading to higher altitude for IR emmissions to space. I assume (1) is the "convective" part but (2) seems like it should be part of the RM. But in that case the RM doesn't explain why an increase of GHGs should lead to warming. I'm sure I'm missing something here but I'd love to know what it is! Rickpoc (talk) 20:45, 10 May 2008 (UTC)

Not sure I understand the problem here. In a pure radiative model, the temperature isn't constant with height, it decreases (assuming a grey atmosphere). Its just a generalisation of the one-layer model. Its not very accurate, at least in part because it can end up with a temperature profile that is unstable: ie, would convect. All a "convective" model adds to a radiative model is to overturn and mix layers that would be unstable. As to why GHGs warms the atmos... does [6] help? William M. Connolley (talk) 19:44, 11 May 2008 (UTC)

I understand the individual explanations of each of the models as to why the GHGs warm the surface. It was the relation beween the models and the role of convection that was confusing me. If I understand you correctly the fact that temperature decreases with height does not depend on convection and would occur in the pure radiative model. Do increased GHGs increase the lapse rate in the pure radiative model? --Rickpoc (talk) 22:12, 17 May 2008 (UTC)

Consider the blanket. how does a blanket make you warmer? by increasing the temperature of the air contacting your skin. change "your" to "earth's", "skin" to "surface", and "blanket" to "GHG". Gzuckier (talk) 15:40, 12 May 2008 (UTC)

Accoding to this link (from the article) the blanket is a bad analogy since it warms by preventing convection. --Rickpoc (talk) 22:12, 17 May 2008 (UTC)

Automatic archiving

Is it OK to add automatic archiving to this page? there seems to be a discussions from 2006 and such lying around, not being useful...
– Apis (talk) 16:25, 15 May 2008 (UTC)

Automatic archiving added.
— Apis (talk) 00:59, 18 May 2008 (UTC)

I am not at all happy about the automatic archiving. I might accept it if the archives were directly accessible. What is no longer visible is vital to the subject and its absence might give the impression of a nonexistent consensus. If the archivist would be so kind as to undo the change directly I should be happy but in the meanwhile I am trying to find out how to do this. --Damorbel (talk) 07:32, 22 May 2008 (UTC)

I have replied to this at Wikipedia:New contributors' help page#Automatic Archiving: "Greenhouse Effect". PrimeHunter (talk) 12:21, 22 May 2008 (UTC)

Real greenhouse

There seems to be at least 3 opinions (one is mine) arguing that the Real Greenhous chapter should be removed. Actually, the only source supporting the claim is one research by Woods at the beginning of 20th century, where is the source criticism in Wikipedia? Has anyone ever reproduced the research? If there is no other sources supporting the claim that real greenhous is not based on greenhouse effect, I strongly agree that the chapter should be deleted. Wikipedia should not show insecure speculations as truth.

If no new references is found in a week, I will delete the chapter. Ok?

212.50.144.26 (talk) 14:24, 15 May 2008 (UTC)

No. This has been discussed many times before and even is supported by an arbitration committee opinion. Raymond Arritt (talk) 15:00, 15 May 2008 (UTC)

(ec) Hmm, I don't think this is controversial (i.e. it's more or less commonly accepted) I'll add another source though.
– Apis (talk) 15:10, 15 May 2008 (UTC)

ok.. as you wish. However, I consider this not proven (show me the facts!) and so it should not be expressed as a known fact. As long as there can be found no links to real research, it is a belief of some people. I assume real greenhouse warms partly from preventing convection, but I would not say preventing radiation is meaningless. Soil at 27 degrees radiates at 460 W/m2. I'm truly disappointed at wikipedia unless 1) the claim that thermal radiation in real greenhouse is meaningless is proven or 2) claim is removed or told as 'some people think radiation is meaningless while some think it is not'

btw, if it has been discussed many times, doesn't that prove it IS controversial, at least as long as someone actually proves it on either way? —Preceding unsigned comment added by 82.128.226.51 (talk) 19:44, 26 May 2008 (UTC)

Oh, one thing: please links that are actual research, not a reference to another reference etc. like this: http://www.pubhort.org/actahort/books/456/456_45.htm —Preceding unsigned comment added by 82.128.226.51 (talk) 19:52, 26 May 2008 (UTC)

The real greenhouse has to be based on that sun warms up the soil and greenhouse slows the loss of heat. It slows the loss down by ALL of the following: 1. prevent convection (and change forced covection to unforced if it is blowing) 2. prevent conduction 3. prevent radiation. The question is if one or more of these are major factors compared to the others. I have not seen any calculations proving it. —Preceding unsigned comment added by 82.128.226.51 (talk) 20:09, 26 May 2008 (UTC)

"This can be demonstrated by opening a small window near the roof of a greenhouse: the temperature will drop considerably". Yes, also my home temperature will drop considerably if I open a window. That doesn't mean I'm warming my home only by preventing convection. I still need to buy electricity or burn some wood. —Preceding unsigned comment added by 82.128.226.51 (talk) 20:15, 26 May 2008 (UTC)

If you open a window, your house would cool by more than the amount you'd expect if preventing IR radiation were the primary function of the window. Ditto GH's. The alternative explanation, physically blocking the motion of air, is correct William M. Connolley (talk) 22:02, 26 May 2008 (UTC)

I missed all this talk. Perhaps the reason that the Woods work hasn't been re-done is that its correct? That the work is old is quite irrelevant William M. Connolley (talk) 22:02, 26 May 2008 (UTC)

Consider a thermos: if you remove the lid the contents will cool much faster than with the lid on. Consider a thermos with only hot air inside, what would happen if you remove the lid?

Anyway, the experiment mentioned in the reference in the article [7] is pretty straightforward, it could be fun (and affordable) to repeat yourself!

As for warming your house: preventing convection doesn't warm your house at all? it only prevents it from cooling off quickly.
— Apis (talk) 01:18, 27 May 2008 (UTC)

Still, I consider this not proven. See http://en.wikipedia.org/wiki/Reproducibility. See also http://en.wikipedia.org/wiki/Pseudoscience. It is clear that the greenhouse actually warms up by sunshine. Why it is warmer than surroundings? It simply keeps the heat inside. And it does this by slowing ALL mentioned heat transfer mechanics. If ANY of the heat transfer mechanics is not blocked, the greenhouse would be almost as cold as the surrounding. Correct in the article should be "Only part of real greenhouse warming is based on greenhouse effect: preventing other heat transfer mechanics (convection, coduction) plays also significant role." So basicly greenhouse is warmed by SUN, keeping the heat inside prevents it from COOLING, just as Apis mentioned. But just like in a house; actual heat origin is something else than insulation.

Also cold fusion was thought to be correct until it was re-done: http://en.wikipedia.org/wiki/Cold_fusion Saying something is correct does not make it the truth. Prove it. —Preceding unsigned comment added by 212.50.144.26 (talk) 07:27, 27 May 2008 (UTC)

There are many reliable sources saying the primary effect at work in a greenhouse is preventing convection. I don't see the article saying that the greenhouse effect has no impact on real greenhouses at all, only (indirectly) that it's insignificant compared to preventing convection. Maybe the wording could be improved in some places though.
—Apis (talk) 20:05, 28 May 2008 (UTC)

Hmm.. actually reference nr 23 emphasizes the effect on radiation properties of the greenhouse, read ahead from page 7. But what is the significance of the different thermal losses? I have not yet seen any reliable calculations or research (other than mr Wood, but that is a single research, not replicated AFAIK) anywhere that would prove any of them is more significant than the others. As long as that kind of proof has not been found, subject should be considered unknown. There are a lot of urban legends that are thought to be true just because they have been repeated enought. —Preceding unsigned comment added by 82.128.226.51 (talk) 21:03, 28 May 2008 (UTC) One more thing; preventing convection is important in any structure that is warmed up (or cooled down) in any way. Would it be of any use to warm a house without any walls? No, but that does not mean that warming a house is based on preventing convection. —Preceding unsigned comment added by 82.128.226.51 (talk) 21:13, 28 May 2008 (UTC)

Alright, I checked the Real greenhouses section and nothing in it is contradicted by [23]. (Of course radiation properties are important for greenhouse coverings!)

The urban legend here is that the greenhouse effect is what's keeping greenhouses warm.

Again, there are many sources confirming this. We don't do any research ourself here, only edit an encyclopedia, so we don't need more proof than that most scientists say so. If you want to dispute this then you will have to come up with something credible that says otherwise.

And again, the warming is not done by preventing convection, in a greenhouse the warming is done by the sun (although some also have additional means of heating). The same is true for a house, the warming is not done by preventing convection but typically by radiators. Preventing convection is what keeps the structure from cooling down.

If you build a greenhouse out of an IR-black material and one of a IR-transparent the heat loss difference would be insignificant compared to not preventing convection. (And [23] actually says that radiation loss increase with increased emissivity.)

If you doubt this then I really do think it would be a fun experiment to test yourself (seriously). Don't know how to get hold of a sheet of rock salt though.
—Apis (talk) 05:44, 29 May 2008 (UTC)

Well, I would say there is 2 urban legends here: One saying that greenhouse is based on greenhouse effect and the other saying greenhouse is based on preventing convection ;-). I would not say that radiation prevention is meaningless; I leave in north and here radiation loss is easily seen for example when temperature is near freezing point; all horizontal levels that are not under roof (protected from heat radiating to space) are often frozen in the morning. I think preventing radiation is more important on dry environments (less atmosphere greenhouse effect) and in night. About the Wood experiment: Replicating the experiment is difficult, because the description is inadequate. For example, there are no physical dimensions mentioned on the experiment. What is the volume of his greenhouse? Also, if I understood correctly, in his greenhouse there was only one wall (?) of glass/rock salt. Real greenhouse size is metres and there is 5 walls radiating the heat away (one up to space). He did his experiment only on sunlight; in real life half of the time is night when sun is not shining. How much heat reserving mass was on his greenhouse? What was around the enclosures, open space or was it in a house?

Calculating the heat transfer by radiation is quite simple using Stefan-Bolzmann law: Approximate heat loss by radiation is at 27 degrees about 460 W/m2. Of cource, the environment radiates back, so the net loss depends on temperature difference. Quick calculations tells that loss is about 6W/m2/K. So if the greenhouse blocks the radiation and the temperature difference is 1 degree, it saves heat (virtually heating) at 6W/m2. With temperature difference of 10 degrees, saving is 60W/m2. But what is the back radiation temperature from atmoshpere to ground? The temperature changes from -60 degrees in 10 km to ~20 degrees in ground? I would say that without blocking radiation, the greenhouse will be about the same temperature than the environment in the morning. So can we say greenhouse effect is insignificant on greenhouse?

Calculating convection savings is quite difficult; formula is simple, but finding the correct h (convection heat-transfer coefficient) seems to be difficult. But of course, also convection prevention is essential. However, using walls to prevent convection is obvious in any heated space! —Preceding unsigned comment added by 82.128.226.51 (talk) 10:24, 29 May 2008 (UTC)

What you say about his experiment is true, there are some uncertainties, that's partly why it would be fun to try I think. I would presume the size of the rock salt sheet one can obtain will determine the size of the boxes. :)

Yes, preventing radiation loss is important in a greenhouse, especially during night, but what has that to do with the greenhouse effect in this case? In a typical greenhouse the ir-black surface inside the greenhouse (the ground and plants) usually have smaller surface area than the greenhouse itself, so if the greenhouse is ir-black that would mean larger radiation loss to the surroundings? How much the surroundings radiate back is kind of hard to say without knowing the exact geometry and radiative properties of it.
—Apis (talk) 11:10, 30 May 2008 (UTC)

Wien's displacement law in Basic Mechanism

It seems the Basic Mechanism section could benefit from a reference to Wien's displacement law, which plays a key role in atmospheric "one-way transparency" of solar radiation. By Wien's law, incoming solar radiation peaks in the visible part of the spectrum around 500 nanometers, corresponding with the sun's surface temperature of 5780 K. In contrast, the earth re-radiates energy in the far infrared part of the spectrum around 10 micrometers, corresponding to the planet's surface temperature of 287 K. The atmosphere, including greenhouse gasses, allow the relatively short-wave incoming radiation to pass through efficiently, while co-called greenhouse gasses interfere with the re-radiation of long-wave infrared waves back into space.

A good definition of the greenhouse effect that emphasizes this concept is given by Lueddecke, Pinter, and McManus in the Journal of Geoscience Education, v.49, n.3, May, 2001, p. 274-279, as, "asymmetry of the atmosphere, in which carbon dioxide, water vapor, and other gases are more transparent to in-coming solar radiation than they are to out-going radiation of heat, thereby keeping the Earth warmer than it would otherwise be."

A source that covers the roles of both Wien's law and the Stefan-Boltzmann law in greenhouse warming is at http://www.downbound.com/Greenhouse_Effect_s/322.htm.

Pradtke (talk) 20:48, 31 May 2008 (UTC)

Intro sentence

Raymond; are you seriously contending 'the atmosphere emits IR that warms the surface'? Later, sure. But not first. If anything, it re-warms the surface by re-emitting IR. You're probably refering to "Greenhouse gases also emit longwave radiation both upward to space and downward to the surface. The downward part of this longwave radiation emitted by the atmosphere is the 'greenhouse effect'." on the greenhouse gas page.

That's wrong, it's both, as the caption says: "The ability of the atmosphere to capture and recycle energy emitted by the Earth surface is the defining characteristic of the greenhouse effect."

Or better yet, dictionary definitions:

"an atmospheric heating phenomenon, caused by short-wave solar radiation being readily transmitted inward through the earth's atmosphere but longer-wavelength heat radiation less readily transmitted outward, owing to its absorption by atmospheric carbon dioxide, water vapor, methane, and other gases"

"The phenomenon whereby the earth's atmosphere traps solar radiation, caused by the presence in the atmosphere of gases such as carbon dioxide, water vapor, and methane that allow incoming sunlight to pass through but absorb heat radiated back from the earth's surface. "

"warming that results when solar radiation is trapped by the atmosphere; caused by atmospheric gases that allow sunshine to pass through but absorb heat that is radiated back from the warmed surface of the earth"

Sln3412 (talk) 18:00, 20 May 2008 (UTC)

The core problem is that we're tripping over ourselves by trying to explain a complex process in a short and pithy sentence. To begin with, we shouldn't be treating absorption and emission as separate processes (as implied for example by Kirchhoff's law). It doesn't help that the dictionary definitions make this specious distinction. I'll post some more thoughts on this later. Raymond Arritt (talk) 18:16, 20 May 2008 (UTC)

Fair enough, but that is what happens, shortwave in warms ground, longwave out warms air, that radiation in the air goes up and down. Just saying the air warms the ground seems at least incomplete. If the GHG weren't there to catch the thermal and move it around, the atmosphere wouldn't heat from it in the first place.

I suppose it depends what you're trying to say, if you're at a macro level or a micro level, perhaps.

Also, why is the analogy "incorrect"? They both stay warmer, that's the "effect". It is an analogy after all. The mechanism being different doesn't make it wrong. But perhaps that's just quibbling.

Sln3412 (talk) 18:36, 20 May 2008 (UTC)

If the GHG weren't there to catch the thermal and move it around, the atmosphere wouldn't heat from it in the first place. That's a common misconception. A substantial part of the atmospheric heating comes from sensible and latent heat transfer from the surface. The problem isn't as simple as the atmosphere absorbing LW radiant energy emitted from the surface and radiating the same energy back to the surface. Raymond Arritt (talk) 19:07, 20 May 2008 (UTC)

I think that "the GHE makes the planet warmer because the planet is heated both by the sun and radiation from the atmos" is by far the clearest, simplest and easiest to understand description. It throws away all the unhelpful "blanket" analogies William M. Connolley (talk) 19:48, 20 May 2008 (UTC)

I meant if the GHG weren't there, the heating from their interaction with thermal IR wouldn't be there. Not that it's the entirety of what's happening.

Right now, "trying to explain a complex process in a short and pithy sentence" there are at least 3 places with it differently: "the process in which the emission of infrared radiation by the atmosphere warms a planet's surface" "The ability of the atmosphere to capture and recycle energy emitted by the Earth surface", and the effect from "the gases present in the atmosphere which reduce the loss of heat into space". All that's being done is some of the 'heat' trying to escape is being sent back down. How hard is it to explain that at a 50,000 foot level.

Why not just use something basically how the IPCC explains it "Much of this thermal radiation emitted by the land and ocean is absorbed by the atmosphere, including clouds, and reradiated back to Earth. This is called the greenhouse effect. The glass walls in a greenhouse reduce airflow and increase the temperature of the air inside. Analogously, but through a different physical process, the Earth’s greenhouse effect warms the surface of the planet."

Sln3412 (talk) 20:36, 20 May 2008 (UTC)

Just as another data point, the AMS Glossary of Meteorology speaks thusly: "The heating effect exerted by the atmosphere upon the earth because certain trace gases in the atmosphere (water vapor, carbon dioxide, etc.) absorb and reemit infrared radiation." William's explanation is essentially the same but is cleaner and goes straight to the practical effect. Raymond Arritt (talk) 21:37, 20 May 2008 (UTC)

(un-indent) It would be good I think for the intro to state simply the GHE itself is the atmosphere sending radition from the surface back down, reducing radiation loss to space, which is loosely analogous in effect to a real greenhouse blocking convection. The emission of IR down that the GHG got from absorbing it coming up keeping things warmer. The main point seems to be the reduction of radiation loss to space. Sln3412 (talk) 00:00, 21 May 2008 (UTC)

Hmm, Correct me if I'm wrong, but that's not entirely accurate either I think, radiation loss to space is equal to what is absorbed from the sun. (When the temperature has reached an equilibrium at least.) The GHE effect changes the equilibrium temperature at the surface. What William said is probably the most compact way to say it. It feels like it's leaving out many important parts of the puzzle though, but thats probably inevitable if one is to summarize it into a short lead section. :S
— Apis (talk) 01:08, 21 May 2008 (UTC)

Yes, it changes the equilibrium, although I'd say level rather than temperature, although both are involved. The point being that shortwave IR in from the sun heats the ground, longwave IR from the ground is absorbed by the GHG, and what is emitted back downwards by the GHG keeps the atmosphere warmer than it would be. This downward emission is the GHE.Sln3412 (talk) 01:51, 21 May 2008 (UTC)

I am a bit perplexed why the introduction doesn't make it clear this IR from the atmosphere that re-warms the ground is the longwave IR that comes from the ground in the first place. I think it is very confusing for the first time reader to just read it's from the atmosphere, it makes it appear as if that was the original source. The start should be a simplified overview of the process/concept as in the graphic even if it's it's not entirely correct except maybe on an abstract level. The details are in the body of the article anyway. Sln3412 (talk) 22:41, 21 May 2008 (UTC)

How about something like this?

The greenhouse effect is the process in which the emission of infrared radiation by an atmosphere that comes from a planet's surface rewarms that surface rather than releasing it to space. The name comes from a loose analogy with the temperature difference due to the capture of air inside a greenhouse compared to the mixed air in the atmosphere outside the greenhouse. The greenhouse effect was discovered by Joseph Fourier in 1824 and first investigated quantitatively by Svante Arrhenius in 1896.

--Sln3412 (talk) 20:58, 27 May 2008 (UTC)

Its not a loose analogy, its an incorrect analogy. And "atmosphere that comes from a planet's surface" sounds odd William M. Connolley (talk) 22:06, 27 May 2008 (UTC)

The IPCC explains it as an analogy. So. The analogy can only be incorrect if the two are not similar in any way. Although that's probably just a matter of interpreting what the word means, since we know both keep things warmer than they otherwise would be -- it would be a false analogy to claim they operate in the same way, yes. But this is not an inductive argument fallacy! It's an analogy to what they do, not how they do it.

Analogy: Similarity in some respects between things that are otherwise dissimilar. A comparison based on such similarity. See synonyms at likeness.

An agreement or similarity in some particulars between things otherwise different; sleep and death, for example, are analogous in that they both share a lack of animation and a recumbent posture.

But yes, that wording about the IR is rather clunky, that's why I said "something like". It's IR from a planet's surface heating the air which then (among other things) reheats the surface. The IR, that went up from the ground, comes back down. In a manner of speaking.

--Sln3412 (talk) 17:58, 28 May 2008 (UTC)

As Raymond said above, it's not as simple as IR from the surface heats the atmosphere, a lot of that heating is not from radiation but is caused by convection for example or as Raymond said "A substantial part of the atmospheric heating comes from sensible and latent heat transfer from the surface". What you are trying to describe is a very simplified radiative model. Such a model is described in the article, but I think it's unnecessary (and difficult to incorporate) in the lead section, and it could be misleading. I agree that the current bit about clouds heating the surface feels rather unsatisfying, but it appears to be correct at least. I don't see why the suggested change would be better? (And it would at least have to be something like "The atmospere absorbs heat transfered from the surface" (I think that's right at least?)).
—Apis (talk) 18:56, 28 May 2008 (UTC)

Since the greenhouse effect is IR (thermal radiation) being emitted from the atmosphere downward re-warming the surface (slowing down the thermal IR transfer from the surface or however you want to phrase it), the other heat transfer mechanisms of the surface seem immaterial. That's why I'm ignoring them, the greenhouse effect is the IR part only, isn't that correct? If not, then it's even more confusing to say "The greenhouse effect is the process in which the emission of infrared radiation by the atmosphere warms a planet's surface."--Sln3412 (talk) 23:06, 28 May 2008 (UTC)

(dedent)

1. "the other heat transfer mechanisms of the surface seem immaterial" – No.
2. "the greenhouse effect is the IR part only, isn't that correct?" – No.
3. "If not, then it's even more confusing to say ..." – No, I'm guessing the only heat transfer downwards is done by radiation.

—Apis (talk) 05:59, 29 May 2008 (UTC)

FWIW the IPCC says radiative and by greenhouse gases and thermal IR.

As far as the intro. Surely it can't be that difficult to explain by overview that sunlight comes down and heats the air and surface, the surface releases this and it heats the air, and the air re-heats the ground, impeding radiation loss, like a greenhouse impedes convective cooling. That is the analogy; they both trap heat so you get the same effect. The fact that real greenhouses trap heat by impeding convection rather than radiation seems immaterial to the point.

I suggest using the AR4 WGI glossary (page 946, Annex 1 at http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_Annexes.pdf) or a paraphrasing.

Greenhouse gases effectively absorb thermal infrared radiation, emitted by the Earth’s surface, by the atmosphere itself due to the same gases, and by clouds. Atmospheric radiation is emitted to all sides, including downward to the Earth’s surface. Thus, greenhouse gases trap heat within the surface-troposphere system. This is called the greenhouse effect.

--Sln3412 (talk) 15:30, 5 June 2008 (UTC)

Should be marked as "Has not been proofed"

78.129.96.207 (talk) 21:28, 2 June 2008 (UTC) Nobody has so far shown any substantial experiment to proofe this effect of CO2. Hence, I would mark this article Fiction.

I'm sorry to tell you that the basics of the greenhouse effect (and CO2's effect), can be shown with a simple highschool experiment. So no, it shouldn't be marked that way. --Kim D. Petersen (talk) 21:32, 2 June 2008 (UTC)

Deficiencies

This greenhouse effect is based on a thermal analysis that is independant of the 2nd law of thermodynamics and simpler misaprehensions like the location of the emission surface when considering the radiation balance. The edit I have just made goes a little way to pointing out a number of these weaknesses in the description. --Damorbel (talk) 20:20, 16 June 2008 (UTC)

The "Deficiencies" edit has been undone at least twice by User:KimDabelsteinPetersen and currently is missing so if you want to see what it is you will have to look in the history. Being familiar with this kind of abusive "undo" I think it may be necessary to take the usual steps to stop it.

You don't mean "independent of" you mean "in contradiction to". You're wrong, of course. Even if you don't really know whats going on, or worse, if you're completely sure you do, don't you think you might give some credit and respect to the many scientists who work on this? You are, effectively, calling them all bozos or charlatans, and thats just not plausible. If your criticism made sense, it would be the #1 argument of the scientific skeptics like Lindzen. But it isn't William M. Connolley (talk) 20:43, 16 June 2008 (UTC)

Kim, I would be surprised if you had time to read my edit before you "undid" it. Would you care to explain yor rapid intervention?--Damorbel (talk) 20:41, 16 June 2008 (UTC)

Easy: we've seen this kind of junk before William M. Connolley (talk) 20:43, 16 June 2008 (UTC)

Re William Connolley - Let us not argue about english. (Is one of your names Kim?) The physics is clear, read any article on thermodynamics, it is one of my specialities. The idea that a cold troposphere could radiate to a warmer surface is clearly incorrect, will you be so kind as to revert the undo? Or will you explain in technical terms to us why the 2nd law doesn't apply so we can understand also?

I quote you " Even if you don't really know whats going on, or worse, if you're completely sure you do, don't you think you might give some credit and respect to the many scientists who work on this? You are, effectively, calling them all bozos or charlatans, and thats just not plausible. If your criticism made sense, it would be the #1 argument of the scientific skeptics like Lindzen. But it isn't"

This is your language not mine. I'm after the science first, the respect bit comes when I see integrity. I think we deserve a better explanation rather this intemperate stuff. Be fair William, you will become very famous, gain a lot of credit and respect, if you show that 2nd law thermodynamics doesn't apply, I shall be leading the pack! Now be a good boy and reverse the undo. --Damorbel (talk) 21:18, 16 June 2008 (UTC)

I'll make this very simple: Wikipedia does not publish original research. And talk pages are not forums where you teach people physics. Get your interpretation published in a reliable source (which in this articles case means peer-reviewed), and then come back. --Kim D. Petersen (talk) 21:19, 16 June 2008 (UTC)

Here you find Falsification Of The Atmospheric CO2 Greenhouse Effects Within The Frame Of Physics by Gerlich/Tscheuschner. The authors wrote me that the paper is under peer review. An important reference there, from the biggest german physical journal is: A. Schack, Der Einfluß des Kohlendioxid-Gehaltes der Luft auf das Klima der Welt (The influence of the carbon dioxide content of the air on the climate of the world), Physikalische Blätter 28, 26-28 (1972) --84.136.41.138 (talk) 21:50, 17 June 2008 (UTC)

No original research here, what is in this article is like saying "balck is white" in thermodynamic terms.It would be a good idea to read the link first before pushing the novel POV that heat can flow unassisted from cold to hot. Please do not demand explanations for such matters, it is undignified. It is the article that says the upper troposphere is colder than the surface, I merely point out that heat transfer in this situation can only be from the surface into the troposphere, the article says it is going the other way. Perhaps you misinterpreted all the people working for the IPCC, I don't know that but I suggest you check, but first of all reverse the undo.--Damorbel (talk) 21:33, 16 June 2008 (UTC)

Get your ideas published - or alternatively realize that heat is only one form of energy, and that convection is only one of several processes happening in an atmosphere. Perhaps you may even want to pick up a text book? --Kim D. Petersen (talk) 22:23, 16 June 2008 (UTC)

Damorbel, the second law of thermodynamics warranties that (in the absense of external work) the net flow of energy between a hot reservoir and a cold one is always towards the cold one. That is still true in the greenhouse effect. Using the numbers in the first diagram, 452 W/m2 is transfered from Earth to the atmosphere and 324 W/m^2 is transferred back, so the net flow is 128 W/m^2 towards the atmosphere. This is in accordance with the second law. You seem to have come to the mistaken conclusion that the individual component flows must also always be exclusively from hot to cold, but this is not the case. Dragons flight (talk) 23:24, 16 June 2008 (UTC)

Dragons flight, nice to have your contribution but your claim "Using the numbers in the first diagram, 452 W/m2 is transfered from Earth to the atmosphere and 324 W/m^2 is transferred back, so the net flow is 128 W/m^2 towards the atmosphere." would imply that energy flow was a vector quantity. The unit of energy is the joule which is a scalar, your idea that energy flow through radiation can behave like a vector and produce an identifiable flux is not valid, electromagnetic power flow is the inner product of the electric and magnetic vectors, a scalar. It is quite possible (infact quite normal) to have an EM field that does not transfer energy, this is why EM waves can be reflected and refracted and precisely why energy cannot.

Further to your analysis you say "the net flow is 128 W/m^2 towards the atmosphere" - nearly correct. Yes there cannot be a downward energy (heat) flow but there is still an (upward) energy flow to the troposphere, it is calculated from the difference of the 4th powers of the surface and tropospheric temperatures, this link provides an extensive explanation of radiative energy transfer of this sort[8], if you check it you will see this is everyday science for some people! --Damorbel (talk) 06:52, 17 June 2008 (UTC)

Kim you say "Get your ideas published " There plenty of books already on thermodynamics "- or alternatively realize that heat is only one form of energy," You are absolutely right, they are not generally mentioned in the Greenhouse effect "and that convection is only one of several processes happening in an atmosphere." Sure, but my problem is with the idea of heat can flow from a low to a higher temperature, convection won't do it for you. "Perhaps you may even want to pick up a text book?" I have Maxwell, Kelvin, Ehrenfest plus a few others on my desk, none describe unassisted heat flow from a cold place to a hot one. In view of this I think you will agree that my edit to the article is an accurate and useful contribution based on standard accepted science with no research content or POV, so I invite you to reverse your deletion and let the article stand on its merits.

([User talk:Damorbel|talk]]) 07:17, 17 June 2008 (UTC)

$Q_{up}\approx A\sigma T_{surface}^{4}$

$Q_{down}\approx (1/2)A\sigma T_{atmosphere}^{4}$

$Q_{net}=Q_{up}-Q_{down}$

There is an upward and downward flow implicit in the work you cite. Dragons flight (talk) 08:13, 17 June 2008 (UTC)

Dragons flight, the article I cited illustrates how thermal control of spacecraft is established. You seem to imagine that these guys ESA has found that the 2nd Law of thermodynamics doesn't apply! Why don't you contact Philippe Poinas at ESA, his email address is all over the doc. and ask him? I would love to see his face while listening to you question! By the way these thermal control check their calculations using a thermal vacuum chamber [9]. Look at the people round the edge, quite a big facility to pay for if the heat transfer theory is all wrong!

By the way the correct formula for radiative heat transfer between element "i" and "j" is Qij = AiFij(Ti4 - Tj4), this is to be found in the ESA document, what it means is that the heat flow via radiation is from the highest temperature part (4th power Ti) to the lower temperature part (4th power Tj), Qij is a magnitude, it is not a vector.--Damorbel (talk) 18:31, 17 June 2008 (UTC)

oceans have warmed 50 percent faster over the last 40 years than previously thought

http://news.smh.com.au/world/oceans-warm-more-quickly-than-suspected-study-20080619-2t0i.html

I believe this refers to:

http://www.nature.com/nature/journal/v453/n7198/edsumm/e080619-12.html

"[The authors'] ocean warming and thermal expansion trends for 1961 to 2003 are about 50 per cent larger than earlier estimates but about 40 per cent smaller for 1993 to 2003, consistent with the recognition that previously estimated rates for the 1990s were biased by instrumental errors. The authors add observational estimates of upper-ocean thermal expansion to other contributions to sea-level rise, and find that the sum of contributions from 1961 to 2003 is in good agreement with their updated estimate of near-global mean sea level."

Does this mean that future sea level rise is expected to be 50% more than previously projected? 12.7.175.2 (talk) 21:17, 18 June 2008 (UTC)

Sounds like fun. This is breaking news so doesn't belong in wiki for a while yet, and when it does the first place is probably global warming William M. Connolley (talk) 23:15, 18 June 2008 (UTC)

greenhouse effect

you should add more detail about what it is and a more recent news on the greenhouse effect — Preceding unsigned comment added by 67.83.135.189 (talk • contribs • WHOIS)

I have been searching to find more references for this article. I found many sites which were based on this article (eg. http://www.newworldencyclopedia.org/entry/Greenhouse_effect). This article appears to be well written but lack references. Juding from it's acceptance and reproductions on the internet most of it appears to be quite sound. I still have had a difficult time finding references to back it up.Veteran0101 (talk) 20:52, 3 September 2008 (UTC)

Talk:Greenhouse effect confined to history?

The only place to find the Talk:Greenhouse effect since 18 June 2008 is in history. For some reason the Talk:Greenhouse since 18 June 2008 has been disappeared. Curiously enough the last item (at present) is dated 18:45, August 20, 2007 (UTC). I suspect an over enthusiastic archiving attempt. Can we please have items since 1/1/2008 back?--Damorbel (talk) 16:15, 18 August 2008 (UTC)

There hasn't been any talk since June 18... (except for some vandalism that was reverted). So i'm not sure what you are talking about. --Kim D. Petersen (talk) 16:34, 18 August 2008 (UTC)

And this stuff [[10]]--Damorbel (talk) 16:45, 18 August 2008 (UTC)

There is nothing there. Take a look at the history since June 18:

1. (cur) (last) 19:34, 18 August 2008 Damorbel (Talk | contribs) (5,814 bytes (→Talk:Greenhouse effect confined to history?) (undo)
2. (cur) (last) 17:53, 18 August 2008 Damorbel (Talk | contribs) (5,039 bytes) (→Talk:Greenhouse effect confined to history?) (undo)
3. (cur) (last) 17:45, 18 August 2008 Damorbel (Talk | contribs) (4,714 bytes) (→Talk:Greenhouse effect confined to history?) (undo)
4. (cur) (last) 17:34, 18 August 2008 KimDabelsteinPetersen (Talk | contribs) (4,528 bytes) (→Talk:Greenhouse effect confined to history?: what are you talking about?) (undo)
5. (cur) (last) 17:15, 18 August 2008 Damorbel (Talk | contribs) (4,272 bytes) (→Talk:Greenhouse effect confined to history?: new section) (undo)
6. (cur) (last) 16:11, 23 July 2008 Captqrunch (Talk | contribs) (43,506 bytes) (→oceans have warmed 50 percent faster over the last 40 years than previously thought) (undo)
7. (cur) (last) 16:10, 23 July 2008 Captqrunch (Talk | contribs) (43,716 bytes) (undo)
8. (cur) (last) 14:18, 7 July 2008 Landon1980 (Talk | contribs) (66,268 bytes) (rv v) (undo)
9. (cur) (last) 14:17, 7 July 2008 160.79.240.164 (Talk) (104 bytes) (←​ Replaced content with ' pat smell ov piss and luvs nush so much ... i hate him with a passion..... laura sweeney poo'ed herself') (undo)
10. (cur) (last) 00:08, 30 June 2008 Jason Patton (Talk | contribs) m (66,268 bytes) (Reverted to revision 220247366 by William M. Connolley. (TW)) (undo)
11. (cur) (last) 22:48, 29 June 2008 SineBot (Talk | contribs) m (66,689 bytes) (Signing comment by 189.71.49.42 - "") (undo)
12. (cur) (last) 22:46, 29 June 2008 189.71.49.42 (Talk) (66,440 bytes) (undo)

I've remove the archiving bots edits - and the large scale edit that you just made. Which edits do you think is missing? --Kim D. Petersen (talk) 17:37, 27 August 2008 (UTC)

That edit #10 removes the vandalism/unrelated talk in #11+#12. #8 removes #9 (same reason). CaptCrunch removed his own edit in #7 with edit #6. What exactly do you think is missing? --Kim D. Petersen (talk) 17:41, 27 August 2008 (UTC)

On pages with automatic archiving this message is posted "NOTE: Before requesting automatic archiving on an article's talk page or a Wikipedia forum, please establish a consensus that archiving is really needed there." What does it mean?--Damorbel (talk) 16:53, 18 August 2008 (UTC)

Kim D. Petersen, don't you find it slightly embarassing that the last contribution to this red hot topic of Greenhouse Effect has a year gap in the discussion? Or perhaps you share the conviction of many that the time for discussion on these is over? I mean people who visit this article for the first, or possibly more times, might believe that a whole year has gone without anybody taking an interest in it. There are many who wish to see dicussion ended on Man Made Global Warming, Greenhouse Effect etc., so I suggest that a large notice be placed here to draw the visitors attention that all disscussion has been hidden away in the archives, just to avoid giving a false impression.--Damorbel (talk) 18:34, 18 August 2008 (UTC)

The greenhouse effect is not a "red hot topic", Global warming may be. And i think you should take a look at WP:TALK for your discussions on the other subjects. Wikipedia is not a discussion forum. --Kim D. Petersen (talk) 17:37, 27 August 2008 (UTC)

What do you mean it is not red hot? Only for those who think the discussion is over. If you think the discussion is over then the polite thing to do is retire and stop interfering.

The article puports to be describing real physical effects. It is quite reasonable to drawn attention to fundamental weaknesses in the science. Perpetual motion proposals are justly criticised because they breach either the first law of thermodynamics or the second law of thermodynamics, this article describes such a system and similar criticism of the greenhouse effect has a place in a responsible encyclopedia. If that, as the article states, radiation from the cold troposphere can raise the temperature of a surface that is already warmer than the troposphere, it is a weird POV that is strictly your own. If you do not cannot accept the basic physics of this criticism then I suggest you consider your position as an editor. This criticism does not deny climate change or global warming, it merely draws attention to an obvious weakness in the explanation that is clearly incorrect.

I suggest an alternative approach would be to replace the unfortunate passages with some better physics, but stop the meddling with the talk archives, this can only be seen as an attempt to hinder the Wiki process. I have only made one small observation about the shakey physics of the article, do you imagine that is the only one? --Damorbel (talk) 21:15, 27 August 2008 (UTC)

I'm sorry - but this talk-page is not the place to teach or learn physics. (please see: WP:TALK) Your misunderstanding about thermodynamics has been pointed out to you before - and is at this point bordering on tendentious. Can you find a single text-book that supplies your argument specifically about the greenhouse effect - no you can't - because you fail to understand that its the net energy transfer that matters. --Kim D. Petersen (talk) 21:32, 27 August 2008 (UTC)

To cite the article "But the temperature of the atmosphere generally decreases with height above the surface, at a rate of roughly 6.5 °C per kilometer on average, until one reaches the stratosphere 10-15 km above the surface." There is an upwards negative temperature gradient, it gets colder with altitude, the article states "Atmospheric radiation is emitted to all sides, including downward to the Earth’s surface. Thus greenhouse gases trap heat within the surface-troposphere system." this is a very strange assertion that needs a non GH effect reference to support it, are you able to provide one? There is no doubt that heat goes from the warm surface to the cold troposphere, perhaps a good reference will make it absolutely clear. There is no way that this has to be in the context of GH effect, to demand one is merely a ruse to keep the article in possession of a limited group of people who wish to restrict the article to their POV, quite contrary to Wiki policy.

By the way what do you mean by "its the net energy transfer that matters"? The energy the article is talking about is heat, the means of transfer is radiation, all I am doing is pointing the error in direction, no big deal.

I repeat, please change the archiving policy to allow six months of discussion, as it was before May 2008--Damorbel (talk) 07:29, 28 August 2008 (UTC)

Greenhouse gasses

This section contradicts the article Black body. The article Black body states that a black body radiates based on its temperature. This section says that the greenhouse gases in the atmosphere radiate and that non greenhouse gases cannot radiate in the infrared. Veteran0101 (talk) 03:16, 29 August 2008 (UTC)

From blackbody: a black body is an object that absorbs all light that falls on it. The atmospheric gases simply don't fit that definition. Vsmith (talk) 03:29, 29 August 2008 (UTC)

Vsmith, Is Fraser crazy? The Sun Emits black body radiation. What makes the Earth's atmoshere different from the Sun's photoshere? This image: this graphic Shows the black body radiation for 5525K(Sun) and 210-310K (Earth). This section contradicts the image. Non-Greenhouse gases emit blackbody radiation according to their temperature.

http://www.ems.psu.edu/~fraser/Bad/BadFAQ/BadGreenhouseFAQ.html

But, the Earth’s atmosphere does act like the Sun (or at least that part of it we see and which sends us energy). Both the Earth’s atmosphere and the Sun’s photosphere (the part that sends us energy) emit radiation for the same basic reason. Although their temperatures differ, they are both emitting (what is nearly) Blackbody radiation because of those temperatures. And while the photosphere is hotter, our atmosphere occupies a much larger fraction of our sky so we get more energy from the latter.

http://www.ems.psu.edu/~fraser/Bad/BadGreenhouse.html

Does the atmosphere reradiate?

One often hears the claim that the atmosphere absorbs radiation emitted by the Earth (correct) and then reradiates it back to Earth (false). The atmosphere radiates because it has a finite temperature, not because it received radiation. When the atmosphere emits radiation, it is not the same radiation (which ceased to exist upon being absorbed) as it received. The radiation absorbed and that emitted do not even have the same spectrum and certainly are not made up of the same photons. The term reradiate is a nonsense term which should never be used to explain anything. Veteran0101 (talk) 23:32, 29 August 2008 (UTC)

Yeah, he's crazy, but I'm crazier :-)

I wasn't arguing with him at all. What is a major source of the temperature of the troposphere? Could it be the IR radiation from earth's surface - seems likely. The IR is absorbed by greenhouse gases and becomes (fleetingly perhaps) stored energy. O2 and N2 just let this IR zip on by. GG's emit IR giving the tropsphere a temperature to measure. Without the GG's - what would the temperature of the atmosphere be? Kinda low maybe cuz O2 & N2 don't give a shit 'bout IR. What would be the blackbody temperature of a GG-less atmosphere? Do non-GGs radiate IR? Hmm, maybe so, if they are the right temperature (hadn't thought that thru before), but - how do they get to that blackbody IR radiating temperature?...

Your contradict tag was seen as a rather gross simplification considering the content it was slapped on (it also overlapped the image quite messily). Yes, the troposphere can be viewed simplistically as a black body, but the goodies are in the details. ... and on and 0n ... Whatever, cheers, Vsmith (talk) 02:02, 30 August 2008 (UTC)

Vsmith, what really gets me about the article is that is states that the non-GG just sit by and contribute nothing. In fact they receive energy from the GG's and because of their temperature DO emit IR. The section clearly states that non-GG cannot absorb or emit IR. This is only 1/2 true.

My understanding, and correct me if I am wrong, is that the GG's capture the IR just like water captures Mircrowaves in a microwave oven. Once the energy is captured the GG's quickly pass this energy on to the surrounding atmosphere. The surrounding atmosphere GG's and non-GG's as always will emit Black Body radiation depending directly on temperature. The GG's capture the IR and the entire atmosphere emits Black Body radiation depending on temperature.

What browser are you using? At no time, that I can see anyway, has the tag been in front of any image on this page.Veteran0101 (talk) 03:13, 30 August 2008 (UTC)

I shifted the tag up to avoid overlap at 800x600 res. Wasn't a browser problem rather a resolution thing. Also removed the additional reference to talk page.

Not sure 'bout the microwave analogy, there's a significant change in wavelength... but maybe so. The image shows a neat blue "blackbody curve" draped over specific frequency spikes, if as stated, O2 and N2 don't absorb at those λs how can they emit them? But, whether or not the whole atmosphere is a blackbody radiator in the IR is rather irrelevant to the detailed discussion of the physical chemistry of the greenhouse gases involved and seems a minor terminology distraction. But, maybe I'm just blind or full of **it. :-) Vsmith (talk) 13:41, 30 August 2008 (UTC)

Thank you. I will remember the trick. The shift does eliminate the problem. It is however browser dependent. I can increase text size and recreate the effect in opera but not firefox. The text size and browser that I normally use does not have a problem with it.Veteran0101 (talk) 17:55, 30 August 2008 (UTC)

There is a confusion being made here. Blackbody radiation is (approximately) the radiation of molecular interaction. Take any material and get it hot and the constituent molecules will bounce off of their neighbors. Since any accelerating charge will emit electromagnetic radiation (e.g. Brehmstralung), the collisions between atoms (which cause local acceleration of their charged constituents) also creates the emission of small amounts of radiation (in the process essentially converting some of the molecules' kinetic energy to radiation). The frequency and violence of those atomic collisions depends on temperature. For gases, liquids, and some solids, the emission spectrum for atomic interactions is approximately continuous and gives rise to a blackbody shape.

By contrast, atoms and molecules can also absorb and emit light based on electronic transitions within the atom or molecule itself (and molecules can also change vibrational or rotational state). Those transitions are quantized and occur independently of the collisions between a molecule and its nearest neighbors. Greenhouse gases have internal transitions that allow them to efficiently absorb infrared radiation, whereas oxygen and nitrogen do not. As Veteran says, the energy captured by these electronic transitions is often (though not always) subsequently transfered to other molecules by collision, and thus energy captured by greenhouse gases ultimately contributes warmth to the whole atmosphere. However the result of that warmth is that both greenhouse gases and non-greenhouse gases engage in atomic collisions that give rise to blackbody emission.

Incidentally the blackbody process also implies that non-greenhouse gases can absorb some infrared radiation, i.e. by running the process in reverse. If a photon arrives during the collision between two molecules it can sometimes be converted into molecular kinetic energy. However, because that is a three phase interaction (i.e. two molecules + photon must be interacting), the rate of reaction is much lower than absorption of infrared by greenhouse gases which is a two phase interaction (i.e. one molecule of greenhouse gas + photon). In practice, the rate of the three phase reaction is neglible in discussion of the greenhouse effect. Dragons flight (talk) 15:52, 30 August 2008 (UTC)

Thank you Dragons flight. I will re-write the article to make it more accurate. I appreciate your input.Veteran0101 (talk) 17:55, 30 August 2008 (UTC)

Dragons flight, I am curious about your statement above " Since any accelerating charge will emit electromagnetic radiation (e.g. Brehmstralung), the collisions between atoms (which cause local acceleration of their charged constituents) also creates the emission of small amounts of radiation (in the process essentially converting some of the molecules' kinetic energy to radiation)" Are you considering that diatomic molecules also emit/absorb in the infrared? I understanding is that the associated energy levels for diatomic molecules are much lower than for molecules such as CO2 that have substantial charge separation. Further, monatomic gases must produce even less radiation since they have closed shells without any possibility of a dipole.

The common diatomic gases O2 & N2 are transparent even when liquid, I would like to see evidence of what radiation they absorb/emit, let alone blackbody. The often made assertion that all materials emit blackbody radiation is quite incorrect, the whole point of Planck's blackbody spectrum is that charge bound to a nucleus does not emit thermal radiation because its energy is quantized, so, if there is no charge free to accelerate indepedently, there can be no radiation.

I think it is not helpful to introduce Bremsstrahlung as an illustration for charge acceleration in connection with the kinetics of molecules, the proper use of the term is for the encounter of free charged particles (protons, ions etc.), free meaning the energy of the incoming particle has no characteristic value e.g. it is not quantised, thus Bremsstrahlung has a continuous spectrum. --Damorbel (talk) 09:28, 11 September 2008 (UTC)

Damorbel, do you understand the two type of spectra and how they are created?

1. - Line - Created by interactions within atoms/molecules. This is why GHG's absorb and emit in the infrared spectrum.
2. - Continuous - Created by interactions between molecules/atoms. Temperature directly determines the frequency and energy of absorption/emisson. Even non GHG's will absorb/emit dependent solely dependent on temperature. Any substance(even diatomic gasses) will emit/absorb infrared radiation when at the right temperature. Stefan–Boltzmann_law Veteran0101 (talk) 01:38, 21 September 2008 (UTC)

Nice of you react Stefan-Boltzman. Since all radiation comes from accelerating charge I would be most interested to know which charge is accelerating and where in the spectrum it radiates. --Damorbel (talk) 20:35, 21 September 2008 (UTC)

Sorry. It seem neither of us understand what the other is talking about. What is your question? Matter when heated or cooled displays two types of spectra, continuous or line. The line spectrum comes from interactions within the atom/molecule. The continuous spectrum comes the interaction with other atoms/molecules. Veteran0101 (talk) 02:09, 22 September 2008 (UTC)

Veteran, if you do not understand that EM radiation comes only from accelerating charge you will get into difficulties with photons and matter. Line spectra arise where the density of atoms and molecules is low, the photons interact with individual molecules and, because the motions are fairly simple, the spectrum is in lines. As the density increases the atoms/molecules interact with each other and, whatever charge they possess is accelerated by, in the case of gasses, collisions that cause the molecules to accelerate relative to each other. In general adjacent atoms/molecules cause the line spectra of isolated atoms etc. to broaden. Solids are even more complex, for example polished metals hardly reflect or absorb at all because the photons encounter the free electrons that make metals conductors. These electrons are not bound to atoms of metal and do not move with them, therefore they neither emit nor absorb EM energy, it is reflected. What actually happens is that residual oxidation or other noneconducting contamination radiate according to their individual, none metallic, characteristics. The two cases you refer to are part of the more general description of photons and matter, you will perhaps recognise that line spectra and continuous spectra seldom come from matter that is in one state only. --Damorbel (talk) 21:00, 22 September 2008 (UTC)

Damorbel, your explaination is not at odds with what I have just said. Basicly what you are saying is that at low densities line spectra predominate and at high densities continuous spectra predominate. What are you getting at? Diatomic and monatic matter can and do radiate in the infrared, if they are at the proper temperature. Point me to your sources so that I may better understand where you are comming from. Veteran0101 (talk) 02:51, 23 September 2008 (UTC)

The matter I raised was from Dragons flight's contribution above, your intervention didn't address the matter as far as I could see. Dragons flight refers to black body radiation from any material including non GHGs, I questioned this, I still do.--Damorbel (talk) 06:13, 23 September 2008 (UTC)

Research the Explainations of Black body radiation. Dragons Flight is quite correct. Any matter heated to approx 300K will emit continuous spectra in the infrared range. Check out this site http://www.spectralcalc.com/blackbody_calculator/blackbody.php . you will find it interesting. Veteran0101 (talk) 11:21, 23 September 2008 (UTC)

Veteran, you are very wide of the mark, the question is about the radiation characteristics of different materials, gases, solids, liquids etc. You do not appear to be aware of the substantial differences for example your link is utterely irrelevant since it treats emissivity as a parameter to be inserted. I have the impression that this subject is fairly new to you. Since the original question was to Dragons Flight who appears to be unable to answer it, perhaps you should allow the matter to rest there.--Damorbel (talk) 20:20, 23 September 2008 (UTC)

I've removed the tag. There is no contradiction, as the above indicates William M. Connolley (talk) 20:35, 30 August 2008 (UTC)

I've removed:

Although these gasses do not react with infrared radiation at the atomic or molecular level, their absolute temperature does cause the atmosphere to emit Black Body, which at room temperature is infrared radiation

which is arguably technically accurate but its far too misleading. "react with IR" is wrong; "interact" would be OK. As I understand it, the only way they cause the atmos to emit IR is by transferring energy through molecular collision. In this sense, all they are doing is increasing the heat capacity of the atmos. The atmos isn't a black body; there is no need to try to reconcile it with one William M. Connolley (talk) 14:15, 31 August 2008 (UTC)

++++

Thank you Connolley, Dragons flight and Vsmith. I have learned more about greenhouse gasses and the greenhouse effect. This article still needs a lot of work. Do you have any ideas of what I could work on here? I would like to document the processes often quoted in the curent ```Climate Change``` discussions. Thank you all for your time. Veteran0101 (talk) 23:24, 31 August 2008 (UTC)

Reradiate

I reverted the term "reradiate."

I am aware of the fact that some people don't like this term, but the term is accepted and completely well understood in the physics community. There is no ambiguity.

I'm sorry that somebody with a website thinks that the term "reradiate" is a nonsense term, but they're wrong. Geoffrey.landis (talk) 18:48, 29 September 2008 (UTC)

A more substantive problem is that a significant part of the heating of the atmosphere is from non-radiative processes, namely sensible and latent heat flux from the surface. How can the atmosphere "re"radiate energy that it didn't absorb radiatively to begin with? I know the term is used in popular explanations of the greenhouse effect, but it still bothers me that we are perpetuating a misconception. Short Brigade Harvester Boris (talk) 19:41, 29 September 2008 (UTC)

Agree with Boris. What this somebody with a website stuff? William M. Connolley (talk) 20:12, 29 September 2008 (UTC)

"Short Brigade Harvester Boris" wrote: "I know the term is used in popular explanations of the greenhouse effect,"

Let me suggest that, in fact, the term is used in popular and technical explanations of the greenhouse effect and radiative heat transfer.

William M. Connolley wrote: "What this somebody with a website stuff?"

The only citation I can see that anybody have given for deleting the term "re-radiate" or "re-emit" seems to be a website. Can you give me any actual Referenceable sources suggesting that the term shouldn't be used?

Geoffrey.landis (talk) 20:35, 29 September 2008 (UTC)

Errrm, so whats your sooper-source for including the term? And what was the site used for removal? William M. Connolley (talk) 20:51, 29 September 2008 (UTC)

What, do I understand that you're reverting to delete the term without having any actual refererence to provide a reason why you're deleting it, so now you're asking me to provide one to you? Try searching Google (google search for the term "reradiate"), which will give you, for example, the definition from Merriam-Webster: "to radiate again or anew; especially : to emit (energy) in the form of radiation after absorbing incident radiation " or the definition from the American Heritage dictionary: "To emit (absorbed radiation) anew: "Different organic materials in the soil reradiate the sun's heat at different rates" Lori Oliwenstein." or the definition from the Brittanica Student encyclopedia.

Or, for that matter, try a google search for the term reradiation. Geoffrey.landis (talk) 21:06, 29 September 2008 (UTC)

You prove Boris point without introspection. Note key: to emit (energy) in the form of radiation after absorbing incident radiation put into powerful bold. Repeat Boris point A more substantive problem is that a significant part of the heating of the atmosphere is from non-radiative processes, namely sensible and latent heat flux from the surface. How can the atmosphere "re"radiate energy that it didn't absorb radiatively to begin with William M. Connolley (talk) 21:25, 29 September 2008 (UTC)

This article is about the greenhouse effect. It's not about ""non-radiative processes" nor about "sensible and latent heat flux emitted from the surface" (I'm not even sure what he thinks he means by that--how do you "emit" a latent heat flux? If it's latent, by definition, it's not "emitted".) The greenhouse effect is about radiative heat transfer, and therefore radiative heat transfer is what I'm discussing. If this were an article about convective heat transfer in the atmosphere, your comment would make sense. Geoffrey.landis (talk) 22:14, 29 September 2008 (UTC)

Yes, this article is about GHE. Which is inextricably linked to energy xfer through Earth atmosphere. Which happen through many process: radiative only one such. Latent heat also very important; not to neglect. Physicist often over-simplify view of Earth atmosphere but this not correct. Restriction of discussion to only radiative phenomena not possible or permissible William M. Connolley (talk) 22:18, 29 September 2008 (UTC)

Please re-read what I wrote. I never wrote "sensible and latent heat flux emitted from the surface" so I'd appreciate your not putting quote marks around something I did not write. Much less following that up by berating me for writing the thing I did not write ('how do you "emit" a latent heat flux?'). Short Brigade Harvester Boris (talk) 00:29, 30 September 2008 (UTC)

We seem to be having some difficulty communcating. This article is about the greenhouse effect, and the text I had inserted was text defining the greenhouse effect. The greenhouse effect is an effect where atmospheric gasses absorb infrared and then reradiate.

It is true that other means of transferring energy to molecules in the atmosphere also cause them to emit infrared radiation. However, in the section under discussion I was defining the greenhouse effect, not "many processes". Geoffrey.landis (talk) 02:23, 30 September 2008 (UTC)

The greenhouse effect is created by the transfer of energy through the atmosphere in all forms. The leading terms in those energy transfers are radiative processes, but it is incorrect to believe that the greenhouse effect is defined only by absorption and reradiation. Some texts incorrectly describe the greenhouse effect that way, but you have to also include non-radiative energy transfers to have a complete and quantitatively correct understanding of the greenhouse effect. Dragons flight (talk) 02:31, 30 September 2008 (UTC)

Citation, please. Geoffrey.landis (talk) 02:55, 30 September 2008 (UTC)

Google "radiative-convective equilibrium" and take your pick. The classic Manabe and Wetherald paper is good as always, and specifically notes the problems with pure radiative equilibrium (as would result from the simple absorb-and-(re)radiate mechanism). Short Brigade Harvester Boris (talk) 03:14, 30 September 2008 (UTC)

We continue to have a difficulty in communication here. I am specifically talking about the definition of the word "greenhouse effect". You seem to be talking about atmospheric thermal models in general. Yes, of course I am aware that the greenhouse effect is not the only thing that needs to be considered in making an accurate model of heat transfer in the atmosphere. I'm not discussing that here because I'm not discussing heat transfer in the atmosphere in general. I had written a sentence defining the greenhouse effect, which is an effect of infrared absorption. If you believe that the definition of the greenhouse effect does not involve infrared absorption, please give a citation stating this.Geoffrey.landis (talk) 03:41, 30 September 2008 (UTC)

For the second time, I ask that you read what I actually have written. I never said "the definition of the greenhouse effect does not involve infrared absorption." Short Brigade Harvester Boris (talk) 03:46, 30 September 2008 (UTC)

Boris, the conversation here incorporates many people, not just you. If you want me to disentangle precisely what I was responding to, in the context: I attempted to define the greenhouse effect. You deleted the term "reradiate" from the definition I wrote with the comment "not "re-radiate", please -- they absorb, and they radiate". You, along with William M. Connolley, mentioned that the radiated energy could have been originally be transfered in other forms. I challenged this, stating that although energy in general is transfered in many forms, the greenhouse effect is specifically about infrared absorption and reradiation. Dragons flight stated "The greenhouse effect is created by the transfer of energy through the atmosphere in all forms." I asked for a citation for that statement, and stated again that the greenhouse effect refers to the absorption of infrared in the atmosphere, a radiative effect, and does not refer to "transfer of energy through the atmosphere in all forms". You jumped in with a citation stating that understanding all forms of energy transfer is neceessary for accurate thermal models of the atmosphere. This is what I'm responding to: the citation you gave in response to the question I asked in response to the statement Dragons flight gave in response to the statement I made that the greenhouse effect involved infrared absorption and reradiation.

I'm getting annoyed with the tabbing here, so I'm going to de-tab and try to start the conversation, in an attempt to get back to the topic. I am trying to stay to a very narrow topic. I'm not trying to discuss every possible form of energy transfer in the atmosphere. I am simply trying to write a definition of the term "greenhouse effect" that is clear and concise. Geoffrey.landis (talk)

Specifically in the context of writing a simple, one sentence definition of what the greenhouse effect is, could you explain clearly what the objection to the use of the word "reradiate" is (in defining the greenhouse effect --I am not explaining heat transfer in the atmosphere in general)? The original comment to justify the deletion of the word reradiate was: "not "re-radiate", please -- they absorb, and they radiate." I have listed the dictionary definitions of the word reradiate, from Merriam-Webster and the American Heritage dictionary. The word seems accurate. It is commonly used in physics. It is commonly used in explanations of the greenhouse effect. Can you give, perhaps, a citation as to why it shouldn't be used on Wikipedia? Geoffrey.landis (talk) 12:58, 30 September 2008 (UTC)

This link was provided above, which I consider a more reliable source than a dictionary.[11] - Atmoz (talk) 13:35, 1 October 2008 (UTC)

I'm getting to the point where I can do little than just repeat myself. Here's what I wrote earlier: The only citation I can see that anybody have given for deleting the term "re-radiate" or "re-emit" seems to be a website. Can you give me any actual referenceable sources suggesting that the term shouldn't be used?

For comparison, I just added three references-- to textbooks from reputable presses-- citing the use of the word "reradiate" in definitions of the greenhouse effect, and I also footnoted three dictionary definitions. The fact that I limited the references to three is merely because I thought three would suffice; it would certainly be possible to add thirty. If you consider the personal site of the Frasers "more reliable than a dictionary," you should re-read Wikipedia:Verifiability#Self-published_sources.

Unless you can cite a source other than a personal opinion website, I see no reason to not use the term, since it is concise, clear, and accurate. Geoffrey.landis (talk) 13:54, 1 October 2008 (UTC)

I disagree. The term is neither clear, concise, nor accurate, as evidenced by this talk page and the footnote on the article. [12] - Atmoz (talk) 16:42, 1 October 2008 (UTC)

Indeed. But I too can't see much to do other than repeat self. It is worth noting that the term reradiate can be confusing. The photons reradiated are not the same as the photons that were previously absorbed, and may be at different frequencies. is *wrong* (as is the use of the word re-radiate): the energy represented by the photons may not have come from photons at all. But we've said this already William M. Connolley (talk) 18:48, 1 October 2008 (UTC)

Correct that we've said it all before. I've cited sources. You? Geoffrey.landis (talk) 19:05, 1 October 2008 (UTC)

Sources for the definition of "reradiate" don't address the dispute. We aren't bothered by the definition of reradiation, but rather we are bothered by your description of the role that reradiation plays in the greenhouse effect. We have been trying to explain to you that reradiation is only a partial source of the atmosphere's thermal radiation. Hence, it is an erroneous oversimplification to explain the atmospheric thermal emissions contributing to the greenhouse effect solely in terms of reradiation. Consensus here is clearly against you right now; please stop re-adding this material. Dragons flight (talk) 19:28, 1 October 2008 (UTC)

As far as I can tell, the claim that the term "reradiate" is inaccurate is WP:OR, in that there have been no citations adduced to support this view (except for the Fraser website, which I would consider to be opinion, not science, and which adduces a different argument, which is that the term is "nonsense") Geoffrey.landis (talk) 19:59, 1 October 2008 (UTC)

The MedCom ArbComm used "the Frazier website" as a RS.[13] Also from that ruling, it appears you may use the term "reradiate", but only as a metaphor. Your addition does not make clear that the term "reradiate" is being used as a metaphor, and not a physical process. - Atmoz (talk) 20:38, 1 October 2008 (UTC)

Well spotted. Though that was from ArbComm, a higher court William M. Connolley (talk) 20:42, 1 October 2008 (UTC)

The term "reradiate" is not a metaphor. Geoffrey.landis (talk) 20:59, 1 October 2008 (UTC)

Are 4 sources really necessary after this sentence? Thus, greenhouse gases trap heat within the surface-troposphere system. - Atmoz (talk) 03:37, 3 October 2008 (UTC)

It is not clear that four references are sufficient. There is apparently some dispute over the actual definition of what the greenhouse effect is, and references seem to be needed.

On the other hand, I notice six inline citations plus five end-references stating that the "greenhouse effect" in the atmosphere is not the same mechanism as the mechanism of physical greenhouses (this information is repeated in three different places in the article); it's possible that these eleven references might be condensed to fewer. Geoffrey.landis (talk) 13:45, 3 October 2008 (UTC)

The debris of a long-settled edit war. Could probably be pared down now William M. Connolley (talk) 19:14, 3 October 2008 (UTC)

No, long settled [14]. Don't get your war mixed with the old one William M. Connolley (talk) 21:30, 3 October 2008 (UTC)

Ah, I see, you were replying to the second comment, not the first. OK; I deleted my comment; feel free, if you like, to delete your comment as well as this one. Geoffrey.landis (talk) 22:12, 3 October 2008 (UTC)

"The Green House effect" is a phrase that refers to the fact that the Earth's average surface temperature is 14C instead of -18C (or there abouts). Basically, the atmosphere stores heat during the day (using several mechanisms) and then keeps the surface temperature higher at night via IR radiation. The phrase "Green House effect" has nothing to do with how heat gets into the atmosphere, it applies only to the increase in average surface temperature because the Earth has an atmosphere. Approximately 25% of the heat in the atmosphere is from non-IR processes (convection and evaporation). Q Science (talk) 18:52, 30 September 2008 (UTC)

Discussing Reradiation

I had stopped editing the article while waiting to see if the informal request for mediation is going to do any good.

This is a long post-- sorry. It seems that the short discussions of reradiate haven't been useful, so maybe a longer analysis, which tries to address the terminology and analyze the physics may help. I'm putting it in a new section, so I can put in some section headings and try to organize my thinking, but this is in effect a continuation of the previous discussion Geoffrey.landis (talk) 18:35, 5 October 2008 (UTC)

Why is reradiation important?

The problem is that the revised version, deleting the term "reradiate," has also deleted any kind of causality from the explanation of the term "greenhouse effect". The current text says that Greenhouse gases effectively absorb thermal infrared radiation emitted by the Earth’s surface, by the atmosphere itself, and by clouds. They also radiate thermal infrared in all directions." But there's no connection between the first statement-- greenhouse gasses absorb-- and the second-- greenhouse gasses radiate. They are as disconncted as my saying "I play the trumpet, and also read science fiction." Here's a question: if absorption weren't disconnected to emission, why would the absorption of upward infrared have any effect on the ground temperature? The temperature of a body doesn't depend on what happens to the outgoing energy after it's radiated; it's the downwelling radiation that matters. If the absorbed radiation isn't reradiated downward, it has no relevance to heating the planet; reradiation is the only reason that the absorption of upward radiation is relevant.

So, at the very best, I'd say that the current rewrite is bad because it has lost an important causal connection. Geoffrey.landis (talk) 18:35, 5 October 2008 (UTC)

Causality can be included without the term "reradiate", see [15].

Also, there was something of a mistake in that section, which you repeat here. Most of the energy absorbed by greenhouse gases is transferred to other molecules via collision prior to the emission of thermal radiation. Hence it is the atmosphere that radiates in all directions, not just the greenhouse gases. This gets at another reason that "reradiates" is a problematic description of the process since the absorbers are a smaller class than the "radiaters". Dragons flight (talk) 19:19, 5 October 2008 (UTC)

Is physics simplifying? Is that good or bad?

To some extent, this seems to be a fundamental difference in approach between physicist's way of viewing the world and a computer modeler's. The heart of this problem is captured by an offhand statement by Connolley: "Physicist often over-simplify view of Earth atmosphere but this not correct."

That's it right there. What physicists call "simplifying," the computer modelers call "oversimplifying."

The physics approach would be to analyze the problem of heat transfer in the atmosphere by breaking it down into the elementary mechanisms and try to understand and name these mechanisms. The computer modeling approach, on the other hand, is apparently that it's irrelevant to break the problem down into elementary parts; it's all a single complicated system, and a computer model has no need to separate out the various mechanisms from one another; it's just one model, and can be as complicated as you like.

Is simplifying correct? Well, yes. Saying, as Connolley does, that you cannot break the problem into parts and you have to define the greenhouse effect as the entirety of heat transfer in the atmosphere is not useful toward understanding. Although all the energy transfer processes are of course linked, the radiative transfer is the part of the process described by the label "the greenhouse effect". Geoffrey.landis (talk) 18:35, 5 October 2008 (UTC)

I am a physicist. I agree with Connolley that your description is too simple. And no, the greenhouse effect is not just the radiative processes. The greenhouse effect refers to the entire set of processes in the earth-atmosphere system that lead to an increased surface temperature above what would be expected if the Earth and sun were simply in radiative equilibrium with no atmosphere. A large portion of that is attributable to the absorption by greenhouse gases, but that is not the whole story. You can discuss the parts of the energy transfer, including radiation, latent heat, convention, etc., but the term "greenhouse effect" refers to the whole process of recycling energy and not just one of the parts. Its not simply a matter of fostering understanding, it is a matter of being correct versus being wrong. Dragons flight (talk) 19:29, 5 October 2008 (UTC)

From listening to you, I'm beginning to think that the modern world is attempting to redefine the greenhouse effect to be "any mechanism by which an atmosphere increases the temperature of a planet above the blackbody thermal equilibrium". Which would be a pity, since by removing mechanism from the definition, the definition becomes mostly useless-- a statement like "a planetary atmosphere increases the surface temperature of a planet due to the greenhouse effect," would thus becomes a tautology. I don't think that this less useful definition has quite yet taken over, though. By the way, let me note that by the definition you cite, the third paragraph of this article ("The greenhouse effect is only one of many factors which affect the temperature of the Earth. Other positive and negative feedbacks dampen or amplify the greenhouse effect.") no longer makes any sense-- you have defined the greenhouse effect as everything that increases the planet's temperature, so there can't be "other" effects. Geoffrey.landis (talk) 03:30, 7 October 2008 (UTC)

Just as an aside, your (GL) statement above displays a surprising lack of familiarity with how atmospheric modeling (or geophysical modeling in general) actually works. "Break(ing) the problem down into elementary parts" is precisely what we do. Short Brigade Harvester Boris (talk) 19:44, 5 October 2008 (UTC)

Is the term "reradiate" nonsense science?

From the commentary, I can disentangle two proposed reasons to delete the term. First, there was a link to a personal opinion website named "badgreenhouse" that expresss an opinion that the term is "nonsense science." However, this is silly. I spent some time debunking this statement, linking to definitions and to widespread use of the term in physics to show that it definitely is not nonsense, before discovering that (although they linked to the website) in fact nobody commenting here was actually advocating the belief that the term is nonsense, and so addressing the misconception expresed on that site is irrelevant to the conversation. So I will assume, since nobody is asserting this, that addressing the claims of the badgreenhouse website is not relevant to the further discussion Geoffrey.landis (talk) 18:35, 5 October 2008 (UTC)

Is thermal transport by latent heat part of the greenhouse effect?

The only real physics in the discussion so far is essentially encapsulated by "Short Brigade Harvester Boris" in the statement "a significant part of the heating of the atmosphere is from non-radiative processes, namely sensible and latent heat flux from the surface."

This is true, but it is not relevant. The true part is that heat is indeed transferred in the atmosphere by non-radiative processes. The irrelevant part is that these non-radiative processes are not known as "the greenhouse effect", unless you chose to define the greenhouse effect as "the sum total of any and all heat transfer processes in the atmosphere."

This is not a useful definition. The greenhouse effect is the part of the heat transfer that is mediated by absorption and reradiation of infrared radiation by atmospheric gasses-- that is, greenhouse gasses-- it is not the entirety of atmospheric thermal transport. This is not to say that there are no other mechanisms of thermal transport, but only to say that these other mechanisms are not part of the definition of the greenhouse effect. On the other hand, latent heat is a critical factor in the understanding of other parts of atmospheric circulation-- it is a large part of what drives atmospheric motion. So it's not the case that you can ignore it in thinking about the atmosphere- it's merely the case that it's defined otherwise than as a part of the definition of the greenhouse effect.

Short Brigade Harvester Boris does not actually talk about why he thinks that latent heat flux in the atmosphere should be considered greenhouse effect, but let's take that as an example and a chance to examine the physics. Here is the cycle by which latent heat is radiated as infrared:

• (1) Water at the surface of the earth evaporates, in the process absorbing thermal energy and storing it in the form of latent heat, resulting in evaporative cooling of the surface,
• (2) the water vapor rises into higher levels of the atmosphere, carried by convective motion.
• (3) the water vapor condenses into either liquid or solid form, releasing latent heat in the process,
• (4) the droplets or crystals transfer this thermal energy to the atmosphere
• (5) the atmosphere radiates in the infrared; half the radiation is upward, half downward

Look at the image - 62% is down, 38% is up. This is related to the fact that the atmosphere is warmer near the surface and suggests that the atmosphere is nearly opaque at those frequencies. Q Science (talk) 22:06, 5 October 2008 (UTC)

• (6) (some of) the downward portion is absorbed by the ground.

This leads to the question: which, if any, of these processes can be described as "greenhouse effect"? The suggested choice would have to be (5) plus (6).

There are several problems with calling this "greenhouse effect".

One problem is simply the definition. It's not true that any and all mechanisms of heat transfer in the atmosphere is the greenhouse effect.

The second problem is a little more specific; it's that this whole cycle does not actually increase the temperature of the Earth. Step six, the absorption of the radiated energy by the ground, is simply returning (some of) the energy that was originally moved upward by evaporative cooling. The net effect is that the efficiency of thermal transport by latent heat motion followed by radiation has to incorporate the fact that, when the heat is eventually converted into sensible form and radiated, only half of the radiation is released upward. (But, as noted later, that's true regardless of the presence or absence of greenhouse gasses).

The cycle described takes water in condensed form, evaporates it, moves it upward, recondenses it, and then the condensed water radiates. The evaporation and recondensation is actually irrelevant; the net effect is simply that the condensed water is moved upward to radiate from a higher altitude. But in terms of the physics of radiation, there's no difference between condensed water radiating across four pi sterradians, half of which is upward, and condensed water radiating across two pi sterradians-- either way, it's two pi upward. If it weren't for absorption and reemission in the atmosphere, it would make no difference if it were radiating from the surface.

The one difference, of course, is that (due to the partial infrared opacity of the atmosphere) the water radiating from a higher altitude radiates more efficiently. So if the motion of thermal energy in the form latent heat is to be considered at all, it is not adding to the greenhouse effect, but subtracting from it. The motion of energy in the form of latent heat has moved the radiating water above some portion of the greenhouse gasses, and thus it can radiate through less optical depth to space.

So, yes, it's an effect that has to be modeled in understanding atmospheric thermal transport, but no, it's not the greenhouse effect.

A third way of asking the question "is this release of latent heat the greenhouse effect?" is to ask "is the amount of greenhouse gasses in the atmosphere relevant to the retention of this thermal energy?" (This requires an assumption that the term "the greenhouse effect" is defined as "an effect that is related in some way to the concentration of greenhouse gasses in the atmosphere." I'll take to be a given here.) So, does the concentration of greenhouses in the atmosphere change the effective thermal radiation by motion of latent heat? Well, no. If there's a net flux of energy in the form of latent heat Q-dot upward, all of that energy goes somewhere. It's either radiated, or transformed into sensible heat and radiated, but eventually it's all radiated, which occurs regardless of the concentration of greenhouse gasses. The net flux converted to infrared radiation is Q-dot upward regardless of greenhouse gas concentration.

(*A couple of footnotes here: The droplets/crystals themselves also directly radiate in the infrared; only a portion of the infrared radiation of the expressed heat is from energy transferred to greenhouse gasses, since water in either liquid or crystal form is actually a reasonably high-emissivity radiator. Also, some of the infrared radiation originated by the latent heat is neither radiated to space nor absorbed by the ground, but absorbed by greenhouse gasses in the atmosphere and reradiated; this part can be described as greenhouse effect; but it also can be described with the term reradiate.)

Boris goes on to ask, "How can the atmosphere "re"radiate energy that it didn't absorb radiatively to begin with?"

Certainly the atmosphere can radiate energy that it didn't absorb radiatively to begin with. I don't think anyone has ever said it can't. But that's not the greenhouse effect. The greenhouse effect is defined by absorbing and reradiating infrared. Geoffrey.landis (talk) 18:35, 5 October 2008 (UTC)

See my comment two sections up. The greenhouse effect is the system of recycling energy that causes an elevated surface temperature. I believe your definition that limits it to the absorption and emission of radiation is simply wrong. Compare to the effect of wearing heavy clothes. We might term this the "overcoat effect". The overcoat effect keeps us warm by limiting conduction and convection, and trapping radiation. In general some of these processes are more important than others in keeping us warm, but we wouldn't want to say that the overcoat effect should be identified with just one of these processes. In the same way, the greenhouse effect is a set of processes that allow the Earth's surface to retain heat, and it would be misleading to identify it with just one heat transfer process. Dragons flight (talk) 19:43, 5 October 2008 (UTC)

On reflection, I think you are right about part of what you say above. If you could magically turn off non-radiative heat transport, then the Earth's surface would be warmer. In other words the negative impact of non-radiative energy flux from the surface exceeds the extra downward thermal radiation it creates by warming the atmosphere. (Ignoring the issue that evaporation is necessary for maintaining the greenhouse gas water vapor.) However, even so, I continue to disagree with your definition of the greenhouse effect. The radiation from the atmosphere is still a result of the totality of processes affecting the temperature of all the atmosphere's consitutients, and not simply reradiation from the limited portion of the atmosphere that consists of greenhouse gases. To suggest otherwise continues to mischaracterize the origin of the radiation that warms the Earth surface. Dragons flight (talk) 22:37, 5 October 2008 (UTC)

A proposed semi-compromise text

Here is my proposed revised text. I think personally that this has gone too far from "oversimplifying" to "overcomplexifying," but at least one commenter has stated that it's not accurate if non-infrared heat transfer is not mentioned, so this is my draft rewrite to incorporate that comment:

Greenhouse gases effectively absorb thermal infrared radiation emitted by the Earth’s surface, by the atmosphere itself, and by clouds; and reradiate this energy in the form thermal infrared in all directions, including downward to the Earth’s surface, thus heating the surface. (Not all thermal emission is reradiation of absorbed infrared; other mechanisms, including flux of latent and sensible heat via convective motion, also convey heat to atmospheric gasses, which is eventually radiated in the form of infrared. For complete modeling of the greenhouse effect, all heat transfer mechanisms, not just radiative heat transfer, must be accounted for). Geoffrey.landis (talk) 18:35, 5 October 2008 (UTC)

The revision that dragons flight made (19:13, 5 October 2008) does put causation back into the description. I won't say it's perfect, but it is clear and readable. Since several of the (later) references include quotes, it doesn't seem out of place to add a direct quote from the IIPCC FAQ "What it the greenhouse effect" to the second citation; this echoes the deleted wording that I originally used, but perhaps if it's a direct quote, and in a citation footnote rather than in the body, it might be acceptable to the people arguing that the word is taboo to use here. This edit, if acceptable, will suffice for my minimum criteria for an acceptable article. Geoffrey.landis (talk) 03:46, 7 October 2008 (UTC)

First paragraph

The first sentence claims that

The Greenhouse effect refers to the change in the thermal equilibrium temperature

which is defined as

Thermal equilibrium is when a system's macroscopic thermal observables have ceased to change with time.

Since the actual temperature changes, perhaps it should say average temperature instead. Another approach might be to simply use the more correct January 2008 version of the first sentence.

The greenhouse effect is the process in which the emission of infrared radiation by the atmosphere warms a planet's surface.

There are additional problems with the current version of this paragraph. Q Science (talk) 17:16, 1 October 2008 (UTC)

I'm happy with the old version William M. Connolley (talk) 15:41, 6 October 2008 (UTC)

Truth and Lies

There are many ideas about the Greenhouse effect, however most is incorrect asuptions and speculation made by scientists that pay no attention to the REAL facts. most of these scientists are the exact same that made the false "global cooling" theory 30 years ago. If anyone could see through all the mindless conjurings of these scientists, they would see that this climate change is a natural process of heating and cooling between ice ages. what today's environmentalists are doing with the projected heating and climate change is taking about 3 points and making a straight line. I for one think this is unacceptable. There is actually substantial scientific evidence through lab studies that CO2 improves the natural life functions of many kinds of organisms, improving the environment. The light of truth here must shine free and bright, cutting back the shadows and lies that fill our world. Firemonkey09 (talk) 00:17, 8 October 2008 (UTC)

Thanks for your comment. Talk pages are for discussing changes to the article, not for sharing personal opinions. WP:TALK has some useful guidance about talk page use. Assuming your comment is suggesting changes to this article:

• Your argument seems to be against global warming, and not the greenhouse effect. Opposition to global warming is outlined in detail at Global warming controversy and Politics of global warming. There seems little point in changing this article to duplicate these other articles here.
• Wikipedia articles require sourcing. If you're proposing changes to this (or any other article) you will need to find reliable referenced material to back your proposed amendments. It's not about the truth, its about verifiability.

At present you haven't made a case for any changes as you haven't provided any sources. If you wish to do so, be my guest as minority views on an article subject have a place in proportion to their importance and verifiability. Some guidelines on inclusion of minority views can be found here and here. Euryalus (talk) 00:32, 8 October 2008 (UTC)

Clarification needed re effect vs greenhouse operation

From my reading, there is a lot of confusion out there because actual greenhouses do not in principle or practice actually employ the real greenhouse effect re reradiation of infrared. A one sentence clarification to this effect in the first para would be helpful imho. Otherwise it takes a lot of reading to get this important point. (Assuming I am not myself just as confused) —The preceding unsigned comment was added by 167.191.250.81 (talk) 18:45, August 20, 2007 (UTC)

Are you sure real greehouse does not apply greenhouse effect at all? So tell me what is the temperature in a greenhouse that does not trap radiation and it's inbound and outbound radiations are balanced and equal? Wouldn't it bee the same than outside? 82.128.226.51 (talk) 17:47, 29 October 2008 (UTC)

Heat Transfer

The question of re-radition (or not) is not particularly important to an article describing the Greenhouse Effect. The right question to put is "Does the Greenhouse Effect require the transfer of thermal energy aka heat from the troposphere to the surface? And must this occur with sufficient intensity to raise the surface temperatue by 33C?" This transfer, should it be required, requires the extraction of heat energy from tropospheric gas at -19C, which would cool it further, and transferring it to a gas on the surface generally agreed to be at 14C or thereabouts; all this without any external work being done!--Damorbel (talk) 20:52, 8 October 2008 (UTC)

You are aware, I hope, that the whole system runs on solar power. I'm not sure what you mean by "without external work being done," but do keep in mind that there's an incident power of 1.3 kW/m2 driving the entire system. The whole system-- incident heating, greenhouse effect, convection, radiation--all comes from that incident energy falling downhill.

You ask "Does the Greenhouse Effect require the transfer of thermal energy aka heat from the troposphere to the surface?" If, by "transfer of thermal energy" you actually mean "transfer of net thermal energy, then the answer is no: energy flows both directions, but (by the Stefan-Boltzmann law) more energy flows from the surface to the upper atmosphere than flows from the upper atmosphere to the surface, so the net transfer of energy is from the surface upward. However, subtracting the downward flow from the upward flow means that the net flow upward from the surface is less than it would be with no atmosphere, and so the surface temperature has to be slightly hotter compensate, and to stay in thermal equilibrium. This is the greenhouse effect.

Clear? Geoffrey.landis (talk) 21:26, 8 October 2008 (UTC)

Having participated in the thermal design design of Earth orbiting satellites I am quite well aware of many matters connected with heat transfer. And you?

I've taught it. Geoffrey.landis (talk) 13:49, 9 October 2008 (UTC)

You say "If, by "transfer of thermal energy" you actually mean "transfer of net thermal energy, then the answer is no: energy flows both directions". Heat transfer is by nature "net", there is no other kind.

Photons move both directions, upward and downward. Net heat transfer is the difference between the energy carried by the two. If, as you say, you wish to define net heat transfer at the only kind of heat transfer (which you can do if you like to define it that way), then the answer to your question is "NO". The net heat transfer is from ground to atmosphere, not vice versa. The greenhouse effect reduces the net heat transfer upward, but does not make it go the other way. --GL

When a system is in thermal equilibrium there are no thermal transfer processes taking place, no temperature differences, no heat transfer, this is the basic science of heat and also common experience.

Should the Sun heat the troposphere, making it warmer than the Earth's surface, heat would be transferred by radiation from CO2, H2O etc. to the surface, this radiation would tend to cool the troposphere because it would remove thermal energy from it; the surface would tend to become warmer.

When the Sun heats the surface it becomes warmer than the troposphere thus heat transfers from the surface to the troposphere, this tends to cool the surface. But the lapse rate, more or less constant over the global surface, ensures that it is always warmer than the troposphere above. Where then is the mechanism that is supposedly warming the surface by 33C? There is nothing coming from the troposphere to the surface that is going to raise the surface temperature!

If the troposphere is at some temperature greater than 0K, it is going to radiate energy according to the Stefan-Boltzmann equation, P= epsilon sigma T^4 A. If you do thermal design of spacecraft, surely you are aware of this; this is the fundamental equation of heat transfer in vacuum. --GL

There is no interpretation of the redundant term "net" that is going to do this!--Damorbel (talk) 06:25, 9 October 2008 (UTC)

Oh dear, not this again. We can try the very very simple explanation, and see if it helps: "the earths surface receives radiation from two sources: the sun, and the atmosphere. It is therefore warmer than if it received radiation from the sun alone". Happy now? William M. Connolley (talk) 07:15, 9 October 2008 (UTC)

At night, the surface of the Earth cools much faster than the atmosphere. After an hour or so, the lower troposphere is warmer than the surface. The resulting radiation keeps the minimum nightly temperature higher than what would result without an atmosphere. This is easy to demonstrate by observing that clear nights are colder than overcast nights because clouds keeps the surface from cooling as fast. (They block the IR windows.) Q Science (talk) 15:41, 9 October 2008 (UTC)

"Oh dear, not this again". Who is claiming that there is no radiation from the troposphere? (I suggest "troposphere", it is more precise.) The whole of my contribution was about heat transfer, the predictions of the Greenhouse Effect are about temperature rise. It is the nature of the heat transfer that governs the rise or fall of temperature. Heat may or may not be transferred by EM radiation, the temperatures of the sources of EM radiation govern the transfer, the mere presence of EM radiation is insufficient to cause heat transfer.

If the Greenhouse Effect is confusing EM radiation with heat transfer then it is indeed necessary to look at "this again".--Damorbel (talk) 09:28, 9 October 2008 (UTC)

EM radiation, by which I assume you mean thermal infrared, is indeed a significant mechanism of heat transfer; and it's the one that's key in understanding the greenhouse effect.

"Darmorbal" wrote: "There is nothing coming from the troposphere to the surface that is going to raise the surface temperature!"

If the troposphere is at some temperature greater than 0K, it is going to radiate energy according to the Stefan-Boltzmann equation, P= epsilon sigma T^4 A. That's the law of physics; everything radiates. The troposphere too; no exceptions. If you do thermal design of spacecraft, surely you are aware of this; this is the fundamental equation of heat rejection in spacecraft. The analysis of the greenhouse effect consists of simply taking careful account of each of the mechanisms of heat transfer upward and downward.

All I can suggest is, do the thermal analysis before you continue. In fact, you can treat this as a spacecraft thermal transfer problem. Start by considering a thermal box in vacuum. Assume that it has an heat dissipation load of, say, 200 watts/m2. Assuming that this load is dissipated entirely by radiation, and let's assume an emissivity (epsilon) of, say, 0.65. What is the equilibrium temperature of the surface? OK, once you've calculated that, suppose that the thermal engineer decides that this is too low, and wants to increase the temperature by putting a single layer of MLI material around it. Assume that this MLI has an absorptivity (in the infrared) of 0.1, emissivity of 0.1, reflectivity 0.85, transparency 0.05. What is the surface temperature now?

Once you've come up with those two answers (equilibrium temperature with no MLI, equilibrium temperature with one layer of MLI material) we can move on and look at the case of planetary atmospheres. If, as you say, you've done spacecraft thermal transfer analyses, this one will be very easy. Feel free to use the Matlab thermal transfer module or even NASTRAN if you've got it (although it's hardly worth firing up NASTRAN for such a simple problem), but keep in mind that you need to make sure that the code you run includes emissivity, reflectivity, and also transparency for the MLI. Geoffrey.landis (talk) 14:12, 9 October 2008 (UTC)

Your equation P= epsilon sigma T^4 is that giving the power into a void at OK. To get the heat transferred between two surfaces you should account for the temperature of the sink also. You do this by taking the difference of the 4th power of both temperatures (T_a⁴ - T_b⁴). It is put better here: [16] where you can play about with some figures to convince yourself. --Damorbel (talk) 15:09, 9 October 2008 (UTC)

You taught thermal transfer and you used P= epsilon sigma T^4 as heat transfer? Did you mention that this only gives the heat transfer into 0K? For a real thermal analysis you need to replace T^4 with (T_a⁴ - T_b⁴).

As I said earlier, infrared travels both directions. When you say " you need to replace T^4 with (T_a⁴ - T_b⁴)", what you are saying here is that you need to account for the absorbed infrared flux as well as the emitted flux, so since the atmosphere is radiating downward a flux proportional to its temperature to the fourth power, you have to subtract a term for the downward flux.

Exactly. We're saying the same thing, two different ways. You're on the right track here.

So: can you solve the simple thermal equilibrium problem I posed earlier? Go ahead and solve it using an engineering simplification if you like, that's fine. Matlab may help. Once you solve the case of a simple single-layer insulation, you are halfway there to solving the greenhouse effect for a semitransparent atmosphere. I encourage you: do the numbers. There is no better way to understand the physics than to work through the problems, with numbers. Geoffrey.landis (talk) 03:03, 10 October 2008 (UTC)

What do you mean "Photons move both directions, upward and downward."? Do you feel that an analysis with photons will show that the cold troposphere is warming the Earth's hotter surface somehow? This is absurd! Did your students not pull you to bits about this? --Damorbel (talk) 15:59, 9 October 2008 (UTC)

You wrote (at least I presume it was you; it isn't signed properly) "The greenhouse effect reduces the net heat transfer upward, but does not make it go the other way. --GL" Would you care to describe just how you see the "Greenhouse Effect" actually reducing the net heat transfer upward? I have such difficulty accepting that a cold surface can make a net transfer heat by radiation to a warm surface in order to raise its temperature by 33⁰C. The IPCC claims this to be due to "backradiation" [17] , is there a conflict here? --Damorbel (talk) 16:43, 9 October 2008 (UTC)

Can we please take talk to the physics of the greenhouse effect off this talk page? This isn't an atmospheric physics class. - von Atmoz (talk) 17:18, 9 October 2008 (UTC)

Greenhouse effect isn't physics! I know for some it is just politics now but the logic Atmoz's suggestion there would be no place for the whole article. Do you have a reason for dumping the physics discussion, Atmoz? --Damorbel (talk) 17:28, 9 October 2008 (UTC)

WP:NOTFORUM and WP:SOAP come to mind. - Atmoz (talk) 17:36, 9 October 2008 (UTC)

Point taken. This is a controversial matter with manifest technical contradictions. I have attempted to place a section listing a small number; this section lasted a few minutes. Is there a Wiki policy on this? I understand that controversial matters in Wiki should have some place for sound objections, my objective for the moment is to check the matter out in order to be as constructive as possible, I have no taste for edit wars and so forth.--Damorbel (talk) 18:12, 9 October 2008 (UTC)

I have attempted to place a section listing a small number; this section lasted a few minutes. Don't know what you mean. Can you point to the diff please? the predictions of the Greenhouse Effect are about temperature rise - not really; we're mostly talking about steady state here William M. Connolley (talk) 07:51, 10 October 2008 (UTC)

The section I contributed (and its deletion!) it to be seen here [[18]] 8 minutes, even though discussed beforehand. Error - "a small number of deficiencies;

William, a "temperature rise" is also a rise when it is above the equilibrium. Being a knowledgeable authority on Greenhouse matters you will know that the alleged rise has been occuring with time also, but with a short perpective this appears as a "steady state".--Damorbel (talk) 08:52, 10 October 2008 (UTC)

Oh right, well your addition was obviously unacceptable. Lets try getting the time-dependent confusion out of the way: in the real world, things do vary with time, and the GHE effect varies as concnetrations of GHG's change. But we can forget all about that for a moment while we discuss the basics, specifcally your objection The greenhouse effect is described in this article as “ the process in which the emission of infrared radiation by the atmosphere warms a planet's surface”. Such a process would breach the second law of thermodynamics. So: we can consider the steady state. I wrote above: the earths surface receives radiation from two sources: the sun, and the atmosphere. It is therefore warmer than if it received radiation from the sun alone. Do you have any problem with that, in the time-independent case of an idealised non-rotating planet with only radiative transport? William M. Connolley (talk) 09:44, 10 October 2008 (UTC)

Mr. Connolley, you wrote (09:44, 10 October 2008) "time-independent case of an idealised non-rotating planet with only radiative transport? "Idealised non-rotating planet? with only radiative transport?" What is this? Yet another Greenhouse effect? Do try again, I know you can do better.--Damorbel (talk) 11:37, 10 October 2008 (UTC)

It seems like a better idea to study the idealised version first, and agree on that. Maths is below, also here, do let us know how you get on William M. Connolley (talk) 12:07, 10 October 2008 (UTC)

Geoffrey wrote (14:12, 9 October 2008) "In fact, you can treat this as a spacecraft thermal transfer problem" Not remotely, it is an planetary problem of multiple heat transfer processes in an atmosphere (gas in a gravitational field). The matters you mention are irrelevant to the defects I have identified. The Greenhouse Effect claims radiation from the troposphere raises the surface temperature above its equilibrium. I object to this because it requires a heat transfer process never previously observed. I invite you to substantiate the claimed warming effect in the light of my objection. You may of course agree with me, and let a note of my objection be put in the article.--Damorbel (talk) 08:28, 10 October 2008 (UTC)

It can be treated, in simplified form, as a very basic problem indeed. See the maths, which I provided here. Do you disagree with any of that? With your background you will have no trouble understanding it and pointing out any problems William M. Connolley (talk) 11:21, 10 October 2008 (UTC)

Checked your maths, provided here. Actally I looked in the archives [[19]] to find the full background. Your maths is good but it is the wrong physics. Heat flows according to the energy of the photons, i.e. the temp., not the intensity (W/m²) basics are here at hyperphysics. From this you should be sure you get the full meaning of the (T_a⁴ - T_b⁴) term. The explanation you gave in the archives just adds the intensities (W/m²) e.g. "the radiaton downwards at the sfc is S1 + erU^4" and "The radiation up is rT^4; hence rT^4=S1+erU^4 " But the heat transfer is zero unless T⁴ and U⁴ are different, this is what the hyperphysicslink is all about. I have been pushing the temperature hard because GH effect article does not pay attention to it. The argument is the same as that used by a certain Mr. A Einstein when explaining the Photo Electric Effect It is also the basis of the Second Law of Thermodynamics. --Damorbel (talk) 15:01, 10 October 2008 (UTC)

At night, the atmosphere is warmer than the surface. You are trying to use a static analysis and are ignoring the fact that the Earth turns. Q Science (talk) 17:57, 10 October 2008 (UTC)

Q: I certainly am, for these purposes, as a simplification. D: OK, good, we are onto the maths. I'm afraid its not clear to me exactly where you think the (simplified) physics is in error. You accept that (a) the downward radiation at the sfc is S1+erU^4; and that the upwards radiation at the sfc is (b) rT^4. Therefore, in my world, in equilibrium we must have the two terms being equal. You say "But the heat transfer is zero unless T⁴ and U⁴ are different" and refer me off somewhere else. I don't know what you disagree with. Once you have accepted (a) and (b) I don't see what you can do. Please write down what you believe to be the radiation balance of the sfc, in that situation. And if you use titles, get them right: E wasn't a Mr, of course William M. Connolley (talk) 22:28, 11 October 2008 (UTC)

The GHE article [[20]] claims:- "The surface temperature will rise until it generates thermal radiation equivalent to the sum of the incoming solar and infrared radiation" Because the so-called GHGs radiating in the troposphere are at a lower temperature than the surface, this warming claimed for the GH effect is contrary to Einsteins analysis of the Photoelectric Effect and the Second Law of Thermodynamics. The PE effect and 2nd Law both state very clearly that the lower temperature (thus lower energy) radiation cannot increase the temperature (energy) of material already at a higher temperature. To clarify the PE effect. Einstein noted that, however many (many = power) photons struck a surface, no electrons would be ejected unless the individual impacting photons had higher energy than surface (i.e. came from a hotter source). If you don't know about this you should get a course in quantum mechanics [[21]] In your calculations you bundle radiation from the Sun and the Troposphere without taking account of the different temperture of the sources (downward radiation at the sfc is S1+erU^4) S1 is radiation from a source @5780K, U is radiation from a source @254K S1 has no problem warming the surface to 288K but the Troposphere cannot warm the surface to 288K because it is only @254K, you should not really need QMech. to understand this.

A lot of words, but no substance. Once again: I've written down my surface radiation balance, from which my conclusions follow. I've asked you to write down yours, and you haven't. Please do (and for bonus points, also calculate your predicted surface temperature in terms of the given quantities) William M. Connolley (talk) 20:41, 12 October 2008 (UTC)

Ah, I think I see you mistake. Never mind, we can thrash it out later, for now just write down your sfc radiation budget and we'll take it from there William M. Connolley (talk) 21:38, 12 October 2008 (UTC)

By the way, Einstein did this work in 1905, almost certainly before he got his PhD since he submitted his thesis in April. [22] I think he published his PE paper [23] in March 1905, so it was perhaps Herr Einstein, not Mr. --Damorbel (talk) 18:09, 12 October 2008 (UTC)

Yes, if you're going to weasel out of not using Dr/Prof, you need to use Herr. In no way is Mr appropriate William M. Connolley (talk) 20:41, 12 October 2008 (UTC)

Clarification needed re effect vs greenhouse operation

From my reading, there is a lot of confusion out there because actual greenhouses do not in principle or practice actually employ the real greenhouse effect re reradiation of infrared. A one sentence clarification to this effect in the first para would be helpful imho. Otherwise it takes a lot of reading to get this important point. (Assuming I am not myself just as confused) —The preceding unsigned comment was added by 167.191.250.81 (talk) 18:45, August 20, 2007 (UTC)

Are you sure real greehouse does not apply greenhouse effect at all? So tell me what is the temperature in a greenhouse that does not trap radiation and it's inbound and outbound radiations are balanced and equal? Wouldn't it bee the same than outside? 82.128.226.51 (talk) 17:47, 29 October 2008 (UTC)