Talk:Idealized greenhouse model

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Original research?

Is this a generally accepted (or at least acknowledged) model? The article is completely unreferenced, and I get zero Google Scholar hits for "Idealized greenhouse model". In its current form, it probably violates WP:OR. Hqb (talk) 18:23, 13 December 2008 (UTC)[reply]

It is common in many textbooks. I will try to find an online reference. Incredio (talk) 18:27, 13 December 2008 (UTC)[reply]

References now added. Incredio (talk) 18:45, 13 December 2008 (UTC)[reply]

OK, but please include proper title and author information for the anonymous PDF file used as a reference, otherwise it's useless. Hqb (talk) 18:54, 13 December 2008 (UTC)[reply]

This looks like std stuff. Its not OR (well I only skimmed it so I'm assuming its been done properly) William M. Connolley (talk) 20:02, 13 December 2008 (UTC)[reply]

Yeah, I didn't spot anything cranky in the physics; I was mainly concerned about whether the model as presented is generally considered a good approximation of climatological reality (i.e., accounts for most major factors), or whether we were getting into spherical cow territory. Without verifiable references it's hard to tell. Hqb (talk) 20:47, 13 December 2008 (UTC)[reply]

Its not a particularly good representation of reality, at least in the naive version where you interpret one layer as the surface and the other as the atmosphere, but the page correctly notes that you can interpret one layer as the lower and the other as the upper atmosphere (a little appreciated fact, so bonus points there). Its a standard pedagogical construction - I'm surprised it isn't elsewhere on wiki. Its certainly in the talk pages William M. Connolley (talk) 22:15, 13 December 2008 (UTC)[reply]

I think that there is a problem with the physics of the atmosphere. The atmosphere can not radiate with 2σTa^4 that should be only σTa^4 of which half radiates to the ground and the other half to space. —Preceding unsigned comment added by Oin34 (talk • contribs) 12:50, 12 August 2009 (UTC)[reply]

No, it is correct as written in the article. One looks at the energy budget in each direction. For each direction there is F=σTa^4. the article is in total agreement with this speech from David Archer, called The Greenhouse Effect. --Hg6996 (talk) 09:09, 22 May 2013 (UTC)[reply]

Question about albedo

I'm a little confused. The article says that the albedo is 0.30, but the drawing says 0.60. Am I missing something? Q Science (talk) 19:07, 14 December 2008 (UTC)[reply]

Thanks for pointing that out. I clarified the caption. But that is a good idea to draft figures to represent exactly the solutions for Earth, with and without the greenhouse effect, as discussed in the text. I will do that by 2009. Incredio (talk) 02:30, 15 December 2008 (UTC)[reply]

Figures now changed to represent solutions in text. Incredio (talk) 17:22, 15 December 2008 (UTC)[reply]

Non-greyness ?

I wonder if the last sentence is correct:"This is directly related to the non-greyness of the real atmosphere." From what I know, the reason why temperature in the stratosphere is higher than in the upper troposphere is because of the non-transparency, which means "greyness", not due to the non-greyness!? Am I wrong ? --Hg6996 (talk) 09:24, 22 May 2013 (UTC)[reply]

"grey" means that the transmissivity is the same across all wavelengths William M. Connolley (talk) 10:43, 22 May 2013 (UTC)[reply]

Thx a lot, now I got it! I simply wrongly translated the word "greyness". With your help I was able to correct my fault. :-) --Hg6996 (talk) 16:27, 24 May 2013 (UTC)[reply]

Excellent article. I had the same misunderstanding on first reading. Could we add clarification by extending that last sentence: "This is directly related to the non-greyness of the real atmosphere, which absorbs more at the short end of the spectrum." Dave (talk) 12:07, 13 March 2017 (UTC)[reply]

Question about radiative forcing ?

You state: "The radiative forcing for doubling carbon dioxide is 3.71 W m−2" What is the source for this figure? The references you give do not link to anything that can be deemed to be the source. What I fail to understand it how adding carbon dioxide can materially increase global warming once all the radiation within the wave lengths that it can absorb has been absorbed? I want to see how the figure is calculated and need to see the source. Paidion777 (talk) 12:34, 8 September 2015 (UTC)[reply]

You can find the 3.7-forcing-value for example here on page 38. --Hg6996 (talk) 12:48, 25 September 2015 (UTC)[reply]

(i.e., the earth is a black body in the infrared, which is realistic)

A better formulation is: "(The Earth is nearly a black body in the infrared.)"

A realistic value is 0.95.Hensch56 (talk) 14:45, 4 October 2021 (UTC)[reply]

Flat Earth,

The diagrams showing up/down radiation have the Earth as horizontal. Isn't a correction needed for Earth's curvature? Damorbel (talk) 20:20, 14 September 2022 (UTC)[reply]

This article discusses a simple 1-layer radiative-equilibrium model of the atmosphere. That's such a crude model that accounting for the Earth's curvature would have no impact on the overall accuracy.

Given that most of the the effects of interest happen within 20-km of the the Earth's surface, and the planet has a radius of ~6400 km, the effect of curvature is very, very small, even when working with more accurate models. (And, suppliers of satellite climate data actually deliberately supply their data in a form that makes it largely unnecessary for modelers to consider the Earth's curvature.) Rhwentworth (talk) 05:16, 11 June 2023 (UTC)[reply]

Misleading title

The article is titled "Idealized greenhouse effect", yet the article is about just one particular idealized model, when there are actually many such models. It's a bit like title an article "Automobiles" when it is just about the Honda Accord. The article is implying that a very generic term applies to one specific thing, when it doesn't.

At the end of this comment is a taxonomy of just some of the "idealized greenhouse effect" models that exist in textbooks, journal articles, and on the web. Any of the models in the list below could appropriately be called an idealized greenhouse effect model. Yet, the current article is about only a single model from among that long list of models.

What should be done about this mis-titling?

Unfortunately, the choice is somewhat dependent on what one expects to see happen in the future. Options include changing the title to:

Single-layer atmosphere model of the greenhouse effect - this might be appropriate if we didn't expect anything to be added to the article
Layered-atmosphere models of the greenhouse effect - this might be appropriate if we anticipated additional layered-atmosphere model descriptions being added to the article.
Simplified models of the greenhouse effect - this could be appropriate if we intended the article to become a place to collect together various idealized models of the greenhouse effect

The first choice might make sense if it seemed unlikely anyone would add to the article.

The second choice might make sense if we anticipated additional layered models being described in the article. (I could imagine adding at least one, just so the title would make sense.)

The third choice may be over-ambitious, unless we know someone plans to add more models.

Thoughts? Alternatives? Is anyone interested in discussing this choice?

# # #

Taxonomy of idealized greenhouse effect models:

Radiative equilibrium models
- Radiative equilibrium models with discrete atmospheric layers
  - Opaque layers
    - 1-layer model
    - 2-layer or n-layer model
  - "Gray" layers
    - 1-layer model
    - 2-layer or n-layer model
  - Layers with an atmospheric window
    - 1-layer model
    - 2-layer or n-layer model
- Radiative equilibrium models with a continuous atmosphere
Combined radiative and convective equilibrium models
- Combined equilibrium models with 1, 2, or n layers
- Combined equilibrium models a continuous atmosphere
Models based on an "Effective Radiating Level" determined by the greenhouse gas concentration
- Models using a single bulk effective radiating level that summarizes all emissions
- Models using a separate effective radiating level for each wavelength

Rhwentworth (talk) 05:08, 11 June 2023 (UTC)[reply]

I agree with your reasoning. The title and the scope of this article is rather unclear. EMsmile (talk) 08:45, 9 November 2023 (UTC)[reply]

Comparison allowed?

The temperature is the measure of the average heat or thermal energy in a of a solid, liquid, or gaseous medium in a given place. The sum of temperatures as used in the averaging process has no physical meaning. As a result, an average temperature over a wide range over which it varies from one place to another has no direct physical interpretation. Is it permissible to compare a physical quantity such as the radiation temperature with an unphysical quantity? 2003:E5:270C:F200:983C:B7B5:D4DA:D999 (talk) 11:38, 26 July 2023 (UTC)[reply]

It isn't quite clear what you're saying (though if I had to guess I'd say you were repeating an internet meme; if you are, you could link to it). In this idealised model all referenced temperatures are meaningful. If you think any are not meaningful, please specify exactly which one(s) William M. Connolley (talk) 12:48, 26 July 2023 (UTC)[reply]

The problem is that the GMST has no (direct) physical meaning. Since temperature is an intensive quantity, sums of temperatures and also averages have no physical meaning. Strictly speaking, the GMST is not a temperature.

https://www.encyclopedie-environnement.org/en/climate/average-temperature-earth/

1.2. Average temperature? A statistical indicator!

The temperature of a solid, liquid or gaseous medium is a physical quantity that reflects the agitation of the particles that make it up in a given place. The sum of two temperatures therefore has no physical meaning. As a result, an average temperature over a wide range over which it varies from one place to another has no direct physical interpretation. This is therefore the case for the average temperature calculated over the entire surface of the Earth, covering both the warm tropical regions and the cold polar regions. However, this average is a statistical indicator that proves very useful for assessing climate change on a global scale, both in the past and in projection for the coming centuries. The global average temperature reflects changes in climate that can be explained by identifiable underlying physical mechanisms. 2003:E5:272D:4A00:6511:D243:C8D4:3A09 (talk) 18:17, 13 December 2024 (UTC)[reply]

The article says nothing about GMST. I think my previous comment applies William M. Connolley (talk) 20:18, 13 December 2024 (UTC)[reply]

Merge Illustrative model of greenhouse effect on climate change into here?

The following discussion is closed. Please do not modify it. Subsequent comments should be made in a new section. A summary of the conclusions reached follows.

The result of this discussion was no concensus. Chidgk1 (talk) 12:01, 13 December 2023 (UTC)[reply]

My maths is not good enough to fully understand the details but the two articles seem short enough and related enough to merge Chidgk1 (talk) 14:59, 8 November 2023 (UTC)[reply]

Good suggestion, needs looking into. I don't really understand either article title ("idealized model" or "illustrative model"), so finding this all quite confusing. Are there other similar articles that we should consider at the some time? I've only worked on greenhouse effect so far. EMsmile (talk) 08:48, 9 November 2023 (UTC)[reply]
If it is decided to keep Illustrative model of greenhouse effect on climate change as a separate article perhaps it should be added to "Category:Climate modeling". As the creator of Illustrative model of greenhouse effect on climate change is active on WP but not very often I will leave this discussion open for quite a long time in the hope they will comment. Have also notified Femke for more science input when she is available. Chidgk1 (talk) 13:44, 9 November 2023 (UTC)[reply]
The "idealised model" is the std simplified presentation. The "illustrative model" is rather complex and it isn't clear to me what it is illustrating. I wouldn't merge it into here; the point of this is to present a simplified model, not an enormous wodge of equations William M. Connolley (talk) 09:20, 9 November 2023 (UTC)[reply]

Pinging the creator of Illustrative model of greenhouse effect on climate change, User:Dan Gluck. EMsmile (talk) 08:12, 10 November 2023 (UTC)[reply]

What's the way forward with this now? Pinging User:Chidgk1. EMsmile (talk) 08:54, 13 December 2023 (UTC)[reply]

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.