Talk:Greenhouse effect

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What is the Greenhouse Effect and how does it act on the Earth?

(essay removed)

I've removed the rather lengthy unsourced essay. This page is for discussion of the article.

The essay was previously removed from the article, it is again an essay, no references provided and duplicative of existing content. It's in the history for those interested. Vsmith (talk) 13:40, 30 December 2009 (UTC)

REPLY: This is a geology article that explain clearly and simply what is the Greenhouse effect. There isn’t duplicative or existing content but a simple and complete information about Greenhouse Effect. Now I sign it and I post it below for discussion:

"The Greenhouse effect is the capacity of the atmosphere to retain more or less heat. The Greenhouse effect isn’t always the same. In fact, a more humid atmosphere (with higher content of water vapor) trap more heat than less humid atmosphere; an atmosphere that contains more carbon dioxide or methane, retains more heat than the atmosphere with less content of these gases. When we speak about an increase or decrease of the Greenhouse effect, we refers to the increase or decrease of atmosphere capacity to retain heat: it is obvious that if the atmosphere is able to trap more heat there will be a temperature increase, if the atmosphere is able to trap less heat there will be a temperature decrease.

However, the Greenhouse effect shouldn’t be confused with the simple increase or decrease of the temperature. It isn’t certain that an increase or decrease of the Earth temperature is due to the Greenhouse effect variation: for example when in the past the Sun delivered to Earth more energy, it cause a temperature increase but without necessarily a Greenhouse effect’s change. In this case the atmosphere’s capacity to retain heat didn’t change and the temperature increase is only due to more energy from the Sun, that is came into the Earth's climate system.

Many factors contribute to increase or decrease the Greenhouse effect. Some are internal to the atmosphere (rain, movement of air masses, clouds, water vapor content, carbon dioxide, methane, ...), the others are external (seas’evaporation, carbon dioxide exchange between sea and atmosphere, vegetable and animal’s respiration, bacterial action in the soils, volcanic emissions, ...).

In situation of ideal thermal equilibrium (more energy is absorbed and more is returned), all these factors take part together, some increase the Greenhouse effect, some decrease: the variations cancel each other, keeping the system in a thermal equilibrium. However, the climate system always live in a greater or lesser alteration of its thermal equilibrium: more or less local rain and clouds, high and low pressure fields, evaporation, ... are all phenomena which constantly change the Greenhouse effect on more or less wide area. However in a global view, all these changes cancel each other and keep constant the capacity to retain heat.

The increase or decrease of Greenhouse effect is the tendency, of all these factors without exceptions, to find a balance between them towards a situation of higher or lower temperature. The Greenhouse effect is a rebalancing component of the climate, acting on local area, it is continuously changed on more or less wide area, but it gives a global equilibrium. Just the thermal global equilibrium cancels the changes in local area and the compensations of changes in local area (some positive, others negative) are able to keep a global equilibrium.

The greenhouse effect avoid the Earth system enters into a thermal disequilibrium. When a factor tends to increase the Greenhouse effect, the climate system reacts with cooling effects. When the Greenhouse effect tends to decrease we’ll have heating effects: changing a parameter that unbalance the climate system (solar radiation, evaporation, rain and clouds, activities of plants, animal or bacterial, volcanic activity, greenhouse gas content, ...) the system reacts rebalancing the climate change as locally (faster) as globally (more slowly). If a factor increases the Greenhouse effect (higher content of water vapor or Carbon dioxide, ...), the system will change developing elements that balance the climate system (increase of atmospheric perturbation that release water vapor in the air, greater plant’s development that uses water and carbon dioxide, ...).

The factors that influence the Greenhouse effect are many (some still not well known) and they act differently. Some are narrow phenomena (rainfall, evaporation, wind, clouds, ...). Others have a grater global effect (high or low pressure fields, the movements of air masses, changes in the atmospheric global contents of water vapor, carbon dioxide or methane, ocean currents , ...). some causing changes in short-term (hours, days, weeks) and other in long-term (years, decades, centuries, ...):

1. The evaporation’s increase causes a heating effect: the atmosphere becomes more humid (it increase the water vapor content) and the more humid atmosphere retains more heat;
2. the rainfall increase causes a cooling effect: the atmosphere becomes less humid (losing water vapor) and retains less heat.
3. The cloudiness increasing has a double effect: mainly have a cooling effect by isolating the surface from sun’s rays ( less radiation comes to the earth's surface from the sun, less heat comes into the Earth), in other cases has a heating effect blocking heat radiation from the atmosphere (like a cork).
4. The high and low pressure fields set the movements of warmer or colder air (more or less humid) and they act directly and quickly on the capacity to retain more or less heat from the atmosphere.
5. Movements of air masses, cyclones, ... are strongly connected to what has been said about the rain, clouds, and fields of high or low pressure.
6. Ocean currents play a very important role to rebalance the climate system, same to the air masses movements in the atmosphere.
7. The atmospheric variation of water vapor, carbon dioxide and methane, cause more long-term temperature change and they are balanced by the Greenhouse effect because it’s strongly associated with seas variations and biology variations, such as:
   1. Carbon dioxide plant respiration (the more carbon dioxide = the more plant respiration)
   2. the interchange between atmosphere and oceans of water vapor or carbon dioxide (the more heat = the more interchange of water vapor or carbon dioxide between atmosphere and oceans; but the more water vapor there is in the atmosphere and the more rainfall en clouds we have)
   3. the interchange of methane between land and atmosphere caused by bacteria (the more heat we have the more methane is released into the atmosphere)." —Preceding unsigned comment added by Chicco3 (talk • contribs) 10:45, 30 December 2009 (UTC) --Chicco3 (talk) 12:26, 31 December 2009 (UTC)

MeSSAGE: If there isn't any problem can I add this geology article ? —Preceding unsigned comment added by Chicco3 (talk • contribs) 17:32, 8 January 2010 (UTC)

Sotty, but there are many problems. Parts are wrong, parts are confusing, and parts don't belong here. Do you have a source for this article? --Stephan Schulz (talk) 18:40, 8 January 2010 (UTC)

REPLY: This is my geology italian article (based in many books of geology "Geologia ambientale", "Clima e natura",...") if there are language wrongs or confusing parts, please correct them. Thanks —Preceding unsigned comment added by Chicco3 (talk • contribs) 10:35, 9 January 2010 (UTC)

Proposed rewrite of The distinction between the greenhouse effect and real greenhouses

This section is kind of rambling and redundant. I propose parring it down to

While there are some similarities between the atmospheric "greenhouse effect" and the heating mechanism of the structure from which the name is derived there are important distinctions as well. A greenhouse heats its enclosed space primarily by the prevention of convection cooling. Because a greenhouse is transparent to sunlight, solar energy passes through the enclosure unimpeded and warms the ground inside. The ground in turn warms the enclosed air which continues to heat because unlike the warm air near the surface outside, the trapped air is prevented from rising and pulling in cooler air behind it.

The climatic greenhouse effect is similar in that, like the greenhouse, our atmosphere passes sunlight nearly unimpeded. Both also limit the rate of thermal energy flowing out of the system. The heat trapping mechanisms, however, are very different. The atmosphere, which like a glass enclosure, is transparent to sunlight but it is not transparent to the energy being radiated back up from the earth's surface. Some of this radiant energy is reabsorbed by greenhouse gases and is prevented from escaping into space. This reabsorbed energy keeps the planet warmer, much the way a blanket warms us by preventing our body heat from escaping.

This is a layperson's explanation of the essential difference. I may have boiled it down to much. Comments?JPatterson (talk) 22:40, 3 February 2010 (UTC)

Major rework

Prompted somewhat by the above, I've done a major re-work of several sections of the article which are now (I contend) more accurate as well as shorter, at least in some cases William M. Connolley (talk) 21:45, 4 February 2010 (UTC)

Looks good, other than the link to perhaps the worst definition of sensible heat I have ever laid eyes on :>). Thanks for the effort. Sorry mine fell short.JPatterson (talk) 21:51, 4 February 2010 (UTC)

You're right. I didn't get past the first sentence without going "argh" William M. Connolley (talk) 22:34, 4 February 2010 (UTC)

...so I fixed it William M. Connolley (talk) 23:50, 4 February 2010 (UTC)

Is this correct?"

"In the case of the greenhouse effect the rate of radiation from the Earth to space is limited by the greenhouse". The implication here seems to be that eventually all E->S radiation escapes but that it just takes longer than would be the case sans GHG. I.e. from the ideal model:

The infrared flux density out of the top of the atmosphere:

$F\uparrow =\epsilon \sigma T_{a}^{4}+(1-\epsilon )\sigma T_{s}^{4}$

$F\uparrow$ has units $Wm^{-2}$ so I assume $\sigma T_{s}^{4}$ is the "radiation from earth to space" above. Seems to me the only way $F\uparrow =\sigma T_{s}^{4}$ is if $\epsilon =0$

Is it the rate that is limited or the magnitude? JPatterson (talk) 00:53, 6 February 2010 (UTC)

I have a fun suggestion for you. I'll hold off answering for a while. Get a few of the oh-so-knowledgeable sceptics (you know, the ones so expert on climate science) to try their hand at answering William M. Connolley (talk) 08:35, 6 February 2010 (UTC)

"the ones so expert on climate science". WMC it's much more of a physics question, doncha think? --Damorbel (talk) 11:20, 6 February 2010 (UTC)

No hints I'm afraid. Please put your answer up William M. Connolley (talk) 13:26, 6 February 2010 (UTC)

I noodled through it on my commute home last night. If the outbound radiation suddenly dropped to zero the temperature would not drop instantly but rather decay in some sort of exponential fashion. So there is a time constant involved and it is in fact the rate of energy loss that is being decreased by the GE. I now imagine the atmosphere is rather like a large water tank, with the outbound radiative energy represented by water filling the tank at the top, and the space-bound energy represented by a hole in the bottom. The GHGs make the hole smaller which increases the time the tank would take to empty if the valve were shut off at the top.

Still you've introduced time (rate) into the picture while all of the diagrams show static processes. It would make the article more accessible I think if we could illustrate this time flow of energy somehow.

JPatterson (talk) 17:51, 6 February 2010 (UTC)

It appears that you have assumed that the only way that heat gets into the atmosphere is via radiation. However, convection is also important. As a result, in a cloud free sky, greenhouse gases will always emit more heat than they absorb. Also, when water vapor condenses to form clouds, some of that energy is released to space, increasing the outgoing radiation beyond the equation you presented above. In addition, the clouds themselves emit as blackbodies, adding yet another term to the equation. If the amount of heat from convection and condensation is greater than the amount released by clouds, then the greenhouse gases will still release more heat than they absorb. In that case, adding more greenhouse gases should increase the size of "the hole" by allowing the atmosphere to release energy faster. (At least, that is my understanding.) Q Science (talk) 09:45, 8 February 2010 (UTC)

Q science you make some very weird statements "greenhouse gases will always emit more heat than they absorb" and "when water vapor condenses to form clouds, some of that energy is released to space" etc. etc. Frankly I cannot see how this sort of stuff is going to improve the article. --Damorbel (talk) 10:38, 8 February 2010 (UTC)

Let's assume that greenhouse gases absorb 80 W/m2 via IR radiation. Let's also assume that the atmosphere absorbs 20 W/m2 via conduction/convection (called sensible heat). In this case, the atmosphere now contains an increase of 100 W/m2 of heat. Since the temperature of the atmosphere does not change (in this scenario), the greenhouse gases must release 100 W/m2, 20 W/m2 more than what they absorbed via the same mechanism. Q Science (talk) 19:14, 9 February 2010 (UTC)

I wasn't assuming anything, just trying to get straight in my own mind whether of not GHGs reduce the rate of radiative energy flowing into space (as the article states) or its magnitude. Nor DB, was I proposing my tank analogy be placed in the article. Although I think it has some merit in helping to visualize the effect of GHG on thermal equilibrium (e.g. as the water level rises, pressure at the bottom increases, increasing the amount of outbound flow. When the outbound flow = the inbound flow, the water level (representing temperature) stabilizes. If the hole is made smaller, a new equilibrium is reached at a higher level), but I doubt one could find an RS that backs this up. JPatterson (talk) 14:21, 8 February 2010 (UTC)

Since WMC did not respond to my challenge some time back, I won't respond to his. I do know the answer (after suitably cleaning up the poorly formed question). Those who have read my comments, primarily at the Greenhouse Gas discussion page, and understood what they read, should have no difficulty answering the above question. Here are three observations/guesses about responses. 1) Damorbel won't respond because he knows from experience that he'll get it mostly wrong. 2) WMC will get it mostly right, but his response will be so terse that it will not satisfy the discriminating reader. I think he does this because he likes to leave himself plenty of wiggle room. 3) JP's model doesn't work, in one key respect, in the limit, so he's so lost he may not even believe the correct answer. blackcloak (talk) 07:16, 2 March 2010 (UTC)

Important Omission

Williams rework does not include the important fact that GHGs emit in all directions. --Damorbel (talk) 15:36, 5 February 2010 (UTC)

Isn't that obvious? You get it from the idealised model page, anyway William M. Connolley (talk) 20:40, 5 February 2010 (UTC)

"Isn't that obvious?" Clearly not, without it the uninformed reader might easily take the assertion that "a layer of atmosphere with greenhouses gases will radiate heat downwards" meant that downwards was the only direction of radiation. --Damorbel (talk) 15:27, 7 February 2010 (UTC)

Feel free to add "up and" (being a layer it can't sideways, of course) William M. Connolley (talk) 17:14, 7 February 2010 (UTC)

"Feel free to add "up and"" Er, thanks for the advice WMC but it is my contribution. The way it is written makes it clearer than your suggestion, thank you.--Damorbel (talk) 10:31, 8 February 2010 (UTC)

Pardon my ignorance, but please explain why being a layer precludes it from radiating sideways. If you put a wrought-iron frying pan on the stove to cook pancakes, the handle also gets hot, not just the part of the pan immediately above the burner. Why should this be any different? D. F. Schmidt (talk) 16:06, 14 March 2010 (UTC)

The atmosphere is not far from being spherically symmetrical with no large temperature gradients in the East/West axis so little heat tranfer in this direction. There is a larger temperature gradient from the equator to the poles (35K-70K over 10^4km?) so some transfer here. At the top of the homosphere (85km thick) there is the mesopause, here the temperature is about 190K so the temperature gradient is in the region of 1K/km, about 1000 times greater than that from the equator to the poles.--Damorbel (talk) 19:55, 19 March 2010 (UTC)

Rv: why

I removed the assertion that the GHE is natural [1]. Clearly, the reason we're all intersted is because it is at least in part not natural William M. Connolley (talk) 14:04, 7 February 2010 (UTC)

A natural process that has been "corrupted" by supernatural powers. --- sorry, couldn't resist (the ***** made me do it). Vsmith (talk) 14:54, 7 February 2010 (UTC)

As the natural bit has been re-instated, I'll chime in in support. It is a natural process. The part some of us are "interested in" is covered quite well in the section Enhanced greenhouse effect. Vsmith (talk) 18:36, 8 February 2010 (UTC)

I think it has gone again now. We're back to the status quo ante - say neither - which seems best to me William M. Connolley (talk) 22:10, 8 February 2010 (UTC)

Yeah Nigelj's edit was good. Don't really need to emphasize the natural bit, although that's what some want. Why isn't this article on the probation list? Vsmith (talk) 22:40, 8 February 2010 (UTC)

It seems to me the natural part is adequately covered in the section about black body radiation that explains how much colder it would be without the GHE. JPatterson (talk) 19:26, 9 February 2010 (UTC)

Well, this one is largely about science so we haven't bothered eedit war over it :-) William M. Connolley (talk) 22:55, 8 February 2010 (UTC)

Aren't most about the science? Anyway, added the probation note as our "natural" friend has been warned about it. Vsmith (talk) 02:55, 9 February 2010 (UTC)

Hi, There was some confusion about the term "natural": the heating of earth's surface is part natural and part human, and maybe the increase of Greenhouse effect is not natural,... but the greenhouse effect is obviusly only natural. I added the term "natural" to make this clear. Chicco3 (talk) 20:55, 10 February 2010 (UTC)

Greenhouse gases section

I would like to see a sentence explaining the ranges. Do these represent different estimates or some sort of functional dependence on some other parameter? In other words, is C02's effect somewhere between 9% and 26% because we don't know exactly or does it vary between that range dependent on other factors? JPatterson (talk) 23:37, 8 February 2010 (UTC)

I just noticed this comment, so I apologise for the late response and hope it's still useful. The issue is a semantic one -- since there is overlap between CO2 and other greenhouse gases, it's difficult to define the exact contribution. If you remove everything but CO2, you still get about 26% of the greenhouse effect. If you only remove CO2, it drops by about 9%. StuartH (talk) 03:17, 20 March 2010 (UTC)

'Basic mechanism' edit

I reverted the edit by Nigelj because he has made no attempt to justify it. His edit is confused and unhelpful. If User:Nigelj wants to edit someone elses work let User:Nigelj start here with an explanation of what is needed.--Damorbel (talk) 19:30, 10 February 2010 (UTC)

Hi Damorbel. Which part of my edit do you disagree with? I don't believe it can be all of it because it has so many aspects. I have already tried to explain some WP policies and guidelines to you on my talk page so we won't go into it all again here. Just to say that from what I see, your contribution to that section was quite small, so even if you feel that you own those phrases, you should have no problem with my changes outside of that sentence. Am I right? (I'm still guessing what the actual problem is here) --Nigelj (talk) 20:36, 10 February 2010 (UTC)

Nigelj, in the context of your changes, both Earth and Sun are proper names that should be capitalized. Damorbel, you should at least restore the spelling and grammar fixes that Nigelj made. Q Science (talk) 21:28, 10 February 2010 (UTC)

I made the simple fixes. However, this section still needs work. Q Science (talk) 21:46, 10 February 2010 (UTC)

Only in US English are they, and at the moment the article is an inconsistent mix of the two ( both legitimate) conventions. Also is 'Idealized greenhouse model' a proper noun too? And why is that now linked twice in adjacent paragraphs? --Nigelj (talk) 21:50, 10 February 2010 (UTC)

Well, these articles are "typically" in US English. I left the alternate spelling of "vapor" when it was in paper titles. I left Idealized greenhouse model capitalized because it is an article title, but that may not be a valid reason. Typically, I would capitalize all 3 words in this case, but that is the style "I" follow and not from some standard. I have no problem with multiple links in large articles, but I agree that adjacent paragraphs is too frequent. Please don't read my changes as the only ones I agree with, but as the ones the must be made. Q Science (talk) 00:20, 11 February 2010 (UTC)

Thermal radiation from gases produces an omnidirectional field, this should be clear in the article. I improved WMC's revision which implied that radiation from GHS was only downwards. Any picture of the Earth in the infrared will show the GHGs glowing brightly, i.e. they are the principle way the Earth is cooled. This should be made clear in the article, your editing eliminated this .--Damorbel (talk) 21:44, 10 February 2010 (UTC)

You're going to have to be more specific as to article wording I'm afraid. I'm perfectly aware of the physics of what you're saying and I clarified it elsewhere in the article yesterday too, despite JPat breaking that bit again today. As to your reversion, which part of "a layer of atmosphere with greenhouses gases will absorb heat being radiated upwards from lower layers, and re-radiate it in all directions, both upwards and downwards" (my words) is worse than "a layer of atmosphere with greenhouses gases will radiate heat in all directions, both upwards and downwards" (your words)? In the next sentence I made it even clearer by saying "In order to achieve thermal equilibrium, this results in a warmer surface below, in order still to radiate enough heat back out into deep space from the upper layers". I don't see how you can be finding fault with the physics of that. Please explain, in terms of article wording (not a new or separate explanation of things I'm sure we both understand.) --Nigelj (talk) 22:01, 10 February 2010 (UTC)

Nigel, the problem with your physics is that a gas like CO2 absorbs heat from a warmer source (2nd Law) e.g. the Earth's surface, and tranfers some of the heat by radiation to a cooler sink. The cooler sink may be deep space or an adjacent layer, normally higher up. Let us agree on the physics first and then sort out the wording later, OK? I will check the article to see if it is not necessary to mention the fundamental mechanism at this point. --Damorbel (talk) 10:21, 11 February 2010 (UTC)

'My' physics is the same as 'your' physics, as far as I can see. None of what you mention here was in this sentence in the article, nor was it altered by my edit. How long is this going to take? We still have other problems in this section that you reverted for no reason, and that Q Science has only partially fixed. It doesn't really matter (it's only a Wikipedia article after all), but this seems to be getting a bit laborious now over very little. --Nigelj (talk) 12:34, 11 February 2010 (UTC)

If you both agree on the my/your physics, then, since you're both wrong, you both need to step aside so those who understand the process make the wording changes. Specifically, molecules of CO2, or any greenhouse gas that can accept EM power from the IR field they are bathed, will accept energy quanta (then transferring- or perhaps not- the energy to neighboring N2 and O2), provided the molecules are in a state that allows the corresponding energy transfers, no matter where the IR radiation originated (above or below, in altitude, the receiving level) and no matter what the relative temperatures are. That is is the heating up process. The cooling down side of the process also occurs when the steps are reversed. The relative rates determine the direction of temperature change. This explanation does not violate any law of physics. It may be an "inconvenient truth" to some, and an "incomprehensible truth" to others. blackcloak (talk) 05:59, 2 March 2010 (UTC)

Have you checked the Idealized greenhouse model? The link appears in the pargraph. It is very poor, weird statements like "much cooler and so radiates heat back away from itself at much longer wavelengths," I'll accept the current version of the Greenhouse effect for the present but with this idealized greenhouse model the picture is just becoming blurred, there is no reason to have an extra like the Idealized Greenhouse model.--Damorbel (talk) 21:34, 11 February 2010 (UTC)

So, what is the state of this discussion now? I intend to tidy up that section again soon. Blackcloak, I can assure you that there is no need to go into quantum mechanics to explain the greenhouse effect at this level, nor to bring in conduction between CO2, N2 and O2 within the atmosphere.

I didn't use the term quantum mechanics. If "at this level" is your true motivation, then let's just say up front that this is an oversimplified explanation of a complicated subject and has been deliberately watered down so a 12 year old can understand most of it. As for conduction, where is 99% of the retained atmospheric heat (all sources) stored? If you can answer that question correctly, how did it get there, and how does it leave? But I do understand your point- why would anyone ever choose to read through a whole lot of extraneous material just to understand a simple concept. blackcloak (talk) 22:23, 11 March 2010 (UTC)

Damorbel, I have read it and made some contributions there as well. Now, on the subject of specific article wording suggestions, you have both been utterly mute, so I will list the reasons why I intend to make each change, then make it unless you can come up with better specific wording. Please have a look at WP:TPG to see why that preamble points are important.

I'm talking about the two paragraphs that make up the section 'Basic mechanism'

1. Capitalisation and linking I understand that some people are American and so will insist on capitalising sun and earth whatever happens, so I will give up on that. 'Idealized greenhouse model', however does not need capitalising when it appears mid-sentence and it only needs wikilinking the first time it appears in this section.

   Actually, the Wikipedia style guide specifically says that Sun and Earth should be capitalized. Q Science (talk) 06:10, 11 March 2010 (UTC)

2. Water becomes less I propose to replace "largely because the atmosphere is drier and water vapor - an important greenhouse gas - becomes less" with "largely because the atmosphere is drier there and water vapor is an important greenhouse gas". This is clearer without the parenthetic form and without repeating a synonym for 'drier'.

   Is the word "concentration" too complicated for you to consider? blackcloak (talk) 22:23, 11 March 2010 (UTC)

3. Presentation becomes reasonable I want to replace "the presentation of the Idealized greenhouse model becomes more reasonable" with "the description given by the idealized greenhouse model becomes more realistic". This is because the words I propose mean what we are trying to say, but the words presentation and reasonable are slightly the wrong ones IMHO.
4. Absorb then re-radiate I want to clarify "a layer of atmosphere with greenhouses gases will radiate heat in all directions, both upwards and downwards" by adding something about having to absorb the heat first before re-radiating it: "a layer of atmosphere with greenhouses gases will absorb heat, mostly being radiated upwards from lower layers, and re-radiate it in all directions both upwards and downwards".

   "a layer" does not absorb heat, the greenhouse gases do. How about, for part of this, just say- The greenhouse gas component of the atmosphere at any altitude absorbs heat energy arriving from all directions, and re-radiates heat energy in all directions. And then add something like- Any change in temperature at any one point in the atmosphere due to the inflow and outflow of heat energy is proportional to the net change in the heat energy at that point. "all directions" and "updownwards and downwards" is kinda redundunt (sorry, couldn't resist). And what do you mean by absorbing before re-radiating. This is not correct. The physics does not say this, and any author who does is just another source, even if properly referenced, of hogwash. That situation can only occur at absolute zero. blackcloak (talk) 22:23, 11 March 2010 (UTC)

   This of course assumes that convection, evaporation, and rain do not exits. It also ignores the fact that clear nights are colder than cloudy nights. Q Science (talk) 06:03, 11 March 2010 (UTC)

   I included the words "due to the inflow and outflow of heat energy" for these reasons, and used N's simplified way of referring to electromagnetic IR radiation. I chose not to instigate a confrontation over proper technical terminology. Afterall N has made it clear that there is no place in this article for terms like quantum mechanics. blackcloak (talk) 08:26, 12 March 2010 (UTC)

5. Deep space at 2.7 K There is no need to mention the temperature of deep space in the next phrase - the greenhouse effect would work in the same fashion whatever its value. Therefore I want to change "thereby warming the surface and simultaneously cooling the atmosphere by transmitting heat to deep space at 2.7K" to "In order to achieve thermal equilibrium, this results in a warmer surface below, while radiating enough heat back out into deep space from the upper layers." It is the point where the warming is actually explained: the amount of greenhouse warming is calculated by setting total heat lost equal to total heat received, and saying that whatever had to be radiated upwards from the greenhouse layers to achieve that was also radiated downwards and so is added to the radiation received at the surface. Leaving that out and replacing it with a diversion about 2.7 K was a missed opportunity.
6. Increasing the concentration presently "increases the amount of radiation, and thereby warms the surface more". I suggest "increases the amount of absorption and re-radiation, and thereby leads to a still warmer surface". This reinforces the point made above, that the greenhouse layers are in thermal equilibrium, absorbing and re-radiating heat.

   "thereby leads to" is a nonsequitur. Beyond that it's wrong. At night it leads to a cooler surface. You have to put in the words like, net power or energy movement and averaging over very long time periods in order qualify words like equilibrium. In point of fact, the atmosphere is never at thermal equilibrium. That term can only be used to describe a long time average. blackcloak (talk) 22:23, 11 March 2010 (UTC)

Now, while you preview these changes, remember that I have made all these changes before and that Damorbel reverted all of them, accusing me of "destroying an edit of mine in the process. You made no contribution in the talk pages on this, any particular reason. Wikipedia contributors should always respect and explain, you have done neither. I think respect and explain is an excellent policy, do you?" on my Talk page.

I am happy to work with suggestions for even better improvements than the ones I have proposed here, but I am not going to discuss every aspect of thermodynamics with all-comers. If you have a better wording suggestion, please make it here, and nothing else. I want to get on; this set of edits is only part of the story as we have no mention of higher and lower frequency IR radiation in here yet, and I believe that is important enough for inclusion too, after these fixes are in place. --Nigelj (talk) 21:09, 10 March 2010 (UTC)

I don't care about the caps but your version is clearly better. The stuff about 2.7 K is distracting, and other bits were wrong William M. Connolley (talk) 22:23, 10 March 2010 (UTC)

Saying that the "concentration" of CO2 is increasing is technically correct. However, it is the "mixing ratio" that has increased from 300 ppm to 380 ppm, not the "concentration" (moles per liter). The concentration changes with height, as the pressure goes down so does the concentration. However, the CO2 mixing ratio does not change with height until above 84km. Q Science (talk) 09:01, 12 March 2010 (UTC)

You are correct within the limited scope of your usage of the term "concentration". Check out the sections titled "Qualitative definition" and "Mass versus volume". Note the STP default definition. Also note that Wikipedia seems to define "mixing ratio" only in the context of water vapor. One of the ways pseudoscience develops is by the non-standard usage of terms. blackcloak (talk) 22:06, 12 March 2010 (UTC)

'Basic mechanism' edit /2

What a mess has been made of this description! It is now mumbling and incoherent. What on earth does "Within the region where radiative effects are important the description given by the idealized greenhouse model becomes realistic" mean? Important - what - in social circles? And is there anything clear about "this results in a warmer surface below, in order still to radiate enough heat back out into deep space from the upper layers. Increasing the concentration of the gases increases the amount of absorption and re-radiation, and thereby leads to a still warmer surface.[7]"? If this is the best explanation that Greenhouse effect apologists can manage? It is little wonder that the general public are increasingly doubtful about the whole matter. I don't think you guys have a clue what you are talking about.

Some time ago I pointed out that the radiation field from greenhouse gases is omnidirectional, this doesn't appear any more, no discussion, no explanation, no wonder there is nothing but meaningless twaddle here.--Damorbel (talk) 20:39, 19 March 2010 (UTC)

I second that. The "Basic mechanism" section is terrible and pretty much incomprehensible. The picture is also not good. IMO the article should be flagged by an administrator until this is fixed. 140.160.160.52 (talk)

Explanation of numbers on File:Greenhouse_Effect.svg

(I was about to pose this question in the talk page for the image, but there were indications that that's not the wisest place to do so.) In that file's page's text, it explains the 235 W/m², and gives some other ratios and such. Could someone explain here or elsewhere where the rest of the numbers in the diagram come from? I see that 67 (radiation received by the earth) + 168 (radiation received by the atmosphere) = 235 (radiation delivered by the sun). 40 (lost by the earth, bypassing air) + 452 (radiated back to the air) = 492 ("Heat and energy in the atmosphere") = 324 (retaken by the earth) + 195 (released into space) - 27 (what?). And what's the number "Greenhouse gas absorption: 350" for?

Evidently, at least one of these numbers is incorrect, right? Is the Greenhouse gas value worth mentioning (how are greenhouse gases different from any other gases that keep heat in earth's system)? What's the significance of that value of 350? It seems out of place to me. What am I missing here? —Preceding unsigned comment added by D. F. Schmidt (talk • contribs) 16:54, 14 March 2010 (UTC)

You've got 67 and 168 the wrong way round, but that doesn't matter. For the Earths sfc, from those numbers, 452+40 = 492 and 168+324 = 492 so that all fits. 324+195 = 519 = *atmos* loss. Atmos gain = 67+452 = 519, so that balances too. Solution: you've balanced the wrong numbers William M. Connolley (talk) 22:25, 14 March 2010 (UTC)

The "452 (radiated back to the air)" is actually

• 24 thermals (basically a guess, used to balance the equations)
• 78 evaporation
• 350 surface radiation - assumed to be absorbed by greenhouse gases. However, perhaps 50% is actually absorbed by clouds.

Earth's Annual Global Mean Energy Budget, Kiehl and Trenberth (1997), Bull. Amer. Meteor. Soc., 78, 197-208. Q Science (talk) 05:25, 20 March 2010 (UTC)

Major Error in Comparison of Earth without atmosphere and Earth with Atmosphere

There is a glaring and obvious error in second paragraph. To support the idea that the earth would be -18 or -19 degrees Celsius, the contributor claims that "Earth's surface reflects about 28% of incoming sunlight," referencing the "Introduction to atmospheric chemistry" text. The problem with that citation is that the 28% value includes clouds [which reflect the lion's share of that number]. The Earth's surface albedo is much less [4% is a standard figure]. Without an atmosphere, there would be no clouds...so this becomes a false comparison. —Preceding unsigned comment added by 76.104.101.94 (talk) 18:44, 19 March 2010 (UTC)

There is room for improvement there, I might have a go at it now, but the earth "without a greenhouse effect" is what is actually mentioned, and is a fair comparison. You're right about the surface and clouds, though. StuartH (talk) 03:10, 20 March 2010 (UTC)

Is my edit satisfactory? You're right that it's not all the surface, so just saying the "Earth reflects" is accurate. StuartH (talk) 03:19, 20 March 2010 (UTC)

Maximizing Solar Heat Gain

This article on the greenhouse effects makes the claim that there are two greenhouse effects: one inside a building called a greenhouse and one outside the building called a greenhouse in a place called an atmosphere. For that claim to stand, we have to assume that all literature on the atmospheric greenhouse effect has resorted to a misnomer by calling it a greenhouse effect, since they are supposedly not the same thing. I would like to see evidence of this implied global mistake, as well as some proof showing that the definition of the greenhouse effect is not under dispute. If this cannot be demonstrated, then it is an assertion and should be called out as such or edited out.

Regarding the claim that the greenhouse effect inside a building is due to a lack of convection, this is not based on the design of actual greenhouse buildings. Many greenhouse buildings are deliberately designed for forced or natural convection[2,3]. Recommended air flow for the inside of a professionally built, commercially available greenhouse building is about 1 m/s [1]. This airflow is designed to regulate temperature and humidity, therefore the airflow can occur in the form of outside air ventilation, and/or inside-only air distribution[4].

In light of these facts, a redefinition of the greenhouse effect is in order, but redefining the greenhouse effect for buildings being due to "a lack of or the minimization of convection" instead of "no convection" or "suppressed convection" will now create a new problem since the exact rate of flow at which point the greenhouse disappears or goes away has never been defined and agreed upon in scientific literature. Also, in order for convection to be suppressed, the distance between the glass/plastic panels and the ground would have to be less than two inches, as has been demonstrated for convection cells in double-glass window panels[5].

No single experiment is ever valid unless it has been reproduced by others using the same prescribed techniques, but that is exactly what the Wood's experiment is -- a single experiment that has never been reproduced. As if that wasn't enough, there is a huge problem with the Wood's experiment, namely that it does not attempt to reproduce the conditions inside of an actual greenhouse, such as high humidity and natural or forced convection. What Wood attempted to reproduce was an oven, not a greenhouse. The Wood's experiment is clearly not a scientifically valid experiment and cannot be used to support any claim.

When designing buildings, architects attempt to minimize solar heat gain. This is the opposite of the greenhouse effect, which is to optimize or maximize solar heat gain. Any definition of the greenhouse effect should include the concept of solar heat gain. For maximum solar heat gain, you would want to keep natural convection rates high during the heating cycle -- not suppress them[6]. Only at night would you want to suppress convection in order to keep temperatures and humidity high.

[1] http://www.ces.ncsu.edu/depts/hort/greenhouse_veg/topics/gtp_pages/relhumidity.html

[2] http://cat.inist.fr/?aModele=afficheN&cpsidt=14372166. This also explains why a typical greenhouse has a sloped instead of a flat ceiling, e.g. -- to encourage convection, not suppress it.

[3] http://www.greenhouses-etc.net/ghse-fw/grnhouse_construction.htm. Here we see vents supplied with a greenhouse to deliberately induce convection, yet it does not destroy the greenhouse effect.

[4] http://www.docstoc.com/docs/20542896/Greenhouse-Heating-and-Ventilation-Systems

[5] http://en.wikipedia.org/wiki/Insulated_glazing

[6] http://www.emt-india.net/ECBC/EnergyEfficiencyinHospitals_4Mar2009/Tips/GlazingDesignandSelectionGuide.pdf

HY1802D (talk) 02:00, 20 March 2010 (UTC)

The comparison between the so-called greenhouse effect and a real greenhouse is entirely spurious. The 'Greenhouse effect' explanation tries to make connection between a popular way of keeping a relatively small volume warm and a supposed global warming effect caused by the fact that some gases (the so called Greenhouse gases) absorb and emit radiation by thermal interactions (collisions, vibrations and rotations). Greenhouses are warmed and cooled by this mechanism also but the air inside them (when the windows are closed) does not take part in the general circulation of the atmosphere which, to a considerable extent, is driven by convection thus the heat from sunlight arriving during daylight hours is kept local (trapped?) by the glass walls. Yes, convection is important for heat distribution inside a real greenhouse, also it is important for keeping the world outside the greenhouse reasonably cool in sunlit conditions, it is in this sense that real greenhouses suppress convection.

The Greenhouse effect that is supposed to have climate changing properties is said to arise from the fact that the GHGs are warmed by absorbing radiation in the infrared; it is then said that they tranfer heat back to the surface because GHGs also radiate in the infrared. This latter assertion is completely at variance with the second law of thermodynamics because the surface, globally speaking, is always warmer than the atmosphere and heat transfer is always from warmer places to cooler.

Further, most explanations of the greenhouse effect show a higher level of radiation [2] from the GHGs to the surface that to outer space, this is at variation with the known characteristics of radiation from gases which is omnidirectional. What is worse, in the same diagram [3] GHGs are shown emitting levels of radiation that could only be achieved by a blackbody, this attribution of blackbody properties to a low density gas is quite absurd. --Damorbel (talk) 08:15, 20 March 2010 (UTC)

While you may disagree with the numbers in the chart, do you at least agree that they are consistent? Outflow into space equals inflow from space (the sun). Inflow to the atmosphere equals outflow from the atmosphere. Inflow to the surface equals outflow from the surface. Do you believe that they have to be consistent, or are you willing to tolerate an inbalance? If you believe they are consistent (and should be) but the numbers are wrong, tell us which one/s is/are wrong, guess or choose a reasonable amount, and then tell us how you balance the net flows. Until you provide us with a cogent alternative, there's no way any knowledgeable person will ever take you seriously. As for me, I think the chart is probably fairly accurate and we can safely use it as a good starting point. Elsewhere I notice you are now using the term "globally speaking" in a sense that might be implying NET heat flow (EM radiation, IR in the present case) always moves energy from a warmer body to a cooler body (statistically, anyway). If this is the case, you are right. If this is not the case, you continue to suffer from the delusion that incessant repetition will ultimately lead to the acceptance of garbage ideas. Followers of Lyndon LaRouche believe this kind of thing. blackcloak (talk) 09:13, 20 March 2010 (UTC)

Blackloack, no anount of radiation, blackbody or vibrating gaseous molecules can transfer any heat or thermal energy from a first body to a second that has a higher temperature, the heat always goes from the body with the higher temperature to one with a lower temperature, if you don't understand that all the rest of your physics is a waste of time and you would be extremely injury prone in a kitchen.

History is packed with nutty inventors who have claimed this, you will find a good article about the sincere but illinformed people who pushed this idea here [4]. All explanations of the greenhouse effect are fully signed up to this (relatively) new way of challenging the second law of thermodynamics. You guys are a nice bunch of dreamers but your efforts to explain climate variability is quite contrary to any experimental or theoretical physics. You really should look at these matters as a question of thermodynamics. Or perhaps you think thermodynamics doesn't apply in climatology, just like the guys at EAU/CRU think they don't have to justify their statistical conclusions when contribuing to IPCC ARs.

By the way, why do I have to explain the second law of thermodynamics to you, surely I am not the first? --Damorbel (talk) 12:10, 20 March 2010 (UTC)

Try this. It partially explains why cloudy nights are warmer than clear nights.

E = s (Ta⁴ - Tb⁴)

The net heat flow is from warm to cold, but the rate of heat loss is reduced because cold air is a lot warmer than absolute zero. In order for the number of watts returned to the surface to be higher than the number emitted to space, it must be assumed that the atmosphere is IR opaque, that a warm lower layer is radiating toward the Earth, and that a cold upper layer is emitting toward space.

By the way, a blackbody at 15°C emits 390 W/m2. Since 324 is about 83% of 390, it appears that 324 W/m2 is about correct for an atmosphere at 15°C, which then implies that the emission is from the lower 100 meters of the basically opaque atmosphere. Q Science (talk) 14:49, 20 March 2010 (UTC)

So the greenhouse effect may be caused by clouds, not so much by CO2 then? The clear/cloudy night effect indeed arises from the absorption/reflection characteristics of clouds but aren't you are getting into Svensmark cosmic ray territory here, isn't this rather unusual for you?

What do you mean "the number of watts returned"? Watts are joules per second and in your case they are apparently heating a surface that is warmer than the place the Watts are coming from. Real CRU stuff this, if the facts don't fit the theory, change the facts. Do please keep things simple, do produce an explanation without the cool atmosphere making the surface hotter than the atmosphere itself. (Hint, try the effects of gravity and adiabatic heating, or is that not allowed in "climatology"?)--Damorbel (talk) 17:03, 20 March 2010 (UTC)

What on earth does any of this have to do with cosmic rays? Yes, clouds are a part of the greenhouse effect (although they change the earth's albedo as well, so it's a little complicated), so is water vapour, so is methane, so is ozone, so are CFCs. This is explicitly mentioned in the article, and this article in particular doesn't pretend that the greenhouse effect is due to one thing and one thing alone.

I think it's worth considering that even if it is clouds responsible for the greenhouse effect, they are still violating your imaginary second law of thermodynamics. While you acquaint yourself with the actual theory, I suggest you also review the Dunning–Kruger effect to ensure you haven't become a victim of that as well. The suggestion that every physicist in the world has missed the fact that the entire field of climatology violates one of the most fundamental physical laws is ludicrous. StuartH (talk) 20:36, 20 March 2010 (UTC)

Well, actually you are the first one to describe the second law of thermodynamics in such a special way, i.e. applying it to EM radiation moving in a unidirectional way (warm to cool), while refusing to use the concept of a net flow. I notice you chose not to address any of the numbers in the chart. I notice that your link to perpetual motion is indeed curious since your response to my challenge some time back led to the creation of a perpetual motion machine. As for your use of the term "body" I'll initiate another play-dumb game. When you used the term "body" did you mean a large mass (in particular large enough that common ways of measuring temperature can be used)? Do you also apply the term to single atoms/molecules? (Do you see the beginnings of the trap?) And, yes, I fixed your indents, again. blackcloak (talk) 19:50, 20 March 2010 (UTC)

Blackcloak. You say "actually you are the first one to describe the second law of thermodynamics in such a special way" Heat is transferred with radiation from hotter to cooler by the same law, even the GH Effect seems to recognise this. Haven't you just written something rather foolish? --Damorbel (talk) 13:32, 21 March 2010 (UTC)

There's a good post on that flawed second law of thermodynamics here: [5]. You are arguing using an imaginary law of thermodynamics that physicists do not use. You clearly do not understand the laws of thermodynamics, so it would be a good idea to check that page out. StuartH (talk) 20:01, 20 March 2010 (UTC)

StuartH "What on earth does any of this have to do with cosmic rays?" I suggest you wise up on Svensmark's work. For clouds to form from water vapour cloud condensation nuclei are required, Svensmark's hypothesis is that these arise from cosmic rays [6] thus the presence of clouds (with or without precipitation) is related to the level of cosmic rays passing through the atmosphere. Clouds certainly influence heat transfer in the atmosphere by absorption and and emission but they also reflect radiation which CO2 does not. Reflected radiation, with the reflector configured suitably, can lead to its trapping or exclusion, this is how a vacuum flask works. This trapping effect is one way that "warm cloudy nights" can be explained. Also, by absorbing the Sun's radiation, clouds suppress convection at ground level, transferring it to the cloud top.

StuartH "There's a good post on that flawed second law of thermodynamics here: [7]."The 2nd Law deals only with temperature difference and energy transfer, the energy transfer showing up only as a change in temperature. To quote your link "My boring thermodynamics books and I have long since had a parting of the ways" Where the author goes wrong (as does the greenhouse effect article, see this diagram [8]) is assigning Watts i.e. energy, to a radiation field; how ever many watts are in the radiation field there is no "net" (i.e. heat) energy transfer by the radiation field unless there is also a temperature difference. A red hot mass of iron is generating radiation from every atom but heat is transferred only from high temperature parts to low temperature parts. Now for iron, as a solid, heat is tranferred by vibrations as well as radiation. In a gas heat is trasnsferred by atomic (or molecular) collisions, see kinetic theory as well as radiation for the so called GH gases, there is nothing special about this but it does explain why some gases glow in the infrared when hot and others don't e.g. helium, argon etc. (N.B. these gases do glow when ionised, this does not happen at the Earth's atmospheric temperatures.)--Damorbel (talk) 13:32, 21 March 2010 (UTC)

You're still not conveying a clear understanding of thermodynamics at all. Firstly, Svensmark's speculative hypothesis about the origins of clouds is irrelevant to the question of whether or not clouds violate the second law of thermodynamics. "It's reflection" isn't an answer either, you cannot violate the second law using reflection, and a vacuum flask at no point allows the net flow of heat from cooler to warmer. It inhibits the rate of flow from warm to cool, exactly how the greenhouse effect works.

The diagram doesn't just include the transfer of heat through radiation, it includes all heat flows between the surface and the atmosphere. To demonstrate a violation of the second law, you need to demonstrate where there is a net flow of heat from a cooler body to a warmer body. There are four bodies of interest here -- the sun's surface, the earth's surface, the atmosphere and free space. Every possible combination of these involves a flow of heat from warmer to cooler. It is also assumed in the simplified explanation that the earth's surface is in balance, and so is the atmosphere -- that is, heat in equals heat out and there is no warming over time. Because the greenhouse effect is changing and the planet is warming, this isn't actually true, but it's still a useful explanation. So where is the net flow of heat from cooler to warmer? StuartH (talk) 16:46, 21 March 2010 (UTC)

outdent and break

Think of a laser pointer. It does not matter what you point it at, the number of photons per second remains the same. When you point it at the Sun, the number of photons is the same as when you point it at a wall. Blackbodies (and greenhouse gases) are the same, they emit a certain amount of energy (as photons) depending on their temperature. It does not matter if nearby objects are hotter or colder, the emitted watts per square meter are the same. This is how a cold atmosphere is able to help heat a warmer body. In the case of the atmosphere, energy from a 270K atmosphere raises the temperature of the Earth by about 33K. Notice, the atmosphere does not heat the surface to 288K, but it adds 33K to the temperature produced by the Sun. Q Science (talk) 16:53, 21 March 2010 (UTC)

I have to disagree. A laser is not a black body, it is monochromatic, it output doesn't conform to a blackbody spectrum. The amplitude of its output (at its characteristic frequency) could be that of any number of blackbody temperatures. But a blackbody emits energy on a vast number of frequencies, to be a true black body the spectrum must be the same as that defined by the Planck formula, the Planck spectrum. Even so the laser will transmit energy to a hot body if the irradiation from the laser has a greater amplitude than the amplitude of the blackbody spectrum at that wavelength (and vice-versa), it is just that the word temperature has lost its meaning.

If you consider two adjacent blackbodies (or two blackbodies with their images focussed on each other by a lens) the temperatures are not added, don't you think that would be absurd? They just exchange energy according to the temperature difference, that is how heat works.--84.196.128.194 (talk) 22:09, 21 March 2010 (UTC)