Talk:Greenhouse effect/Archive 8

How should recent edits be handled?

Pinging User:Femke, User:EMsmile, User:RCraig09, User:William M. Connolley

Rhwentworth has been really going to town on the article, making all of the most recent 100+ edits to the article over the last few days, here are the changes since May 28th: https://en.wikipedia.org/w/index.php?title=Greenhouse_effect&diff=1158001706&oldid=1157380106

They added two very sparsely sourced sections at the top on "As a measurable quantity" and "Effect versus cause of the effect", pushing down Concepts and principles.

They also added a large new section called "Concepts and principles: cause of the greenhouse effect" along side the existing section they renamed "Concepts and principles: the greenhouse effect". The new section is focused on lapse rate, which appears to be how their own view of the greenhouse effect is centered. The result, however, appears to be creating an entire second article along side the existing one rather than editing or building on the existing content.

I would like senior editors to step in and say how this situation should be handled. My own view is that this style of editing might be fine for a new article and that many of the edits made are good, but overall the article as it is now is worse than the one of May 28th. If anyone has the time and energy to try and digest all the edits, trim them down, and integrate them into the existing text, they could be constructive. However, it might also just make the most sense to back everything out to that older version: https://en.wikipedia.org/w/index.php?title=Greenhouse_effect&oldid=1157380106 Efbrazil (talk) 17:44, 1 June 2023 (UTC)

Noting that I'm trying to take a couple-month break from editing CC-related articles due to onwiki stress in this topic. So a bit of a shallow answer, and not watching this page.

@Rhwentworth: it's great to see somebody else with a PhD editing! I think WP:ONEDOWN and WP:expert editors can be valuable reads.

Process: Rhwentworth: editing sufficiently slow for others to catch up is really important so that WP:silent consensus can develop. I think there is no consensus apparent on the totality of changes, so the best way forward is a WP:BRD cycle (or BDR) for those pieces where there is disagreement. Copy over the new sections to talk, see which portions have consensus, and then re-add the content which has consensus (probably after improvements)

Content:

• Some of the new text is not in Wikipedia's style, talking too directly to the reader rather than being dispassionate. (For instance "is to be distinguished" rather than "is distinguished"
• I find the long section title difficult to understand. Usually, a section title shouldn't be longer than 2-3 words (per WP:CONCISE, which also applies to section titles).
• I'm not too worried about the citations in the 'As a measurable quantity' section. Those equations are usually sourced to one source. For clarity, it would be good if the source gets repeated once per paragraph
• The citations in Effect versus cause of the effect are insufficient. The source is a bit on the old side; is this still how this topic is explained? It's difficult to show something is WP:DUE with one source as well. I would not include this section.

—Femke 🐦 (talk) 18:34, 1 June 2023 (UTC)

I was just a wee li'l electronics engineer with requisite science background, and I have been overwhelmed by the level of technical detail, and amount of content that has grown the article from 74 to 106 Kbytes in six weeks. I perceive a large gap between the general-audience description in the lead (which is well done) and the seemingly post-doctoral content (in some sections) that is essentially impossible for me to critique in the way Efbrazil urges. If it's intimidating for me (who doesn't even claim to be a Stable Genius), it must be so for much of the general public. As a general approach, I informally propose moving the ultra-techy details (such as those depending on internal links to more arcane techy articles) to a subsidiary article such as Physics of the greenhouse efffect (or similar). —RCraig09 (talk) 21:23, 1 June 2023 (UTC)

User:Femke: Thanks for your feedback. I've done some further editing to try to address many of the issues that you raised.

(Note that "is to be distinguished" was language taken from the IPCC; nonetheless, I've changed it per your suggestion.)

Regarding WP:ONEDOWN, that may be part of the conflict... My sense is that the "greenhouse effect" is properly a topic for graduate students. So, in keeping with that, I've been writing at a level that I would be comfortable seeing in a class for college freshman. Yet, I have a concern that other editors might want the text to be at about a 9th grade level, which I think would preclude any substantial content. Any advice on how to resolve the issue of what target-level to aim for? In the absence of guidance, I'm worried that could create an impasse.

I'd strongly prefer BDR over WP:BRD in this situation. Rhwentworth (talk) 08:00, 2 June 2023 (UTC)

I'm not sure what age 9th grade or college freshman would be, but I'm thinking the appropriate age for the lead would be about 16, and 18 for the rest of the text. Some elements may need like one year of physics at uni to understand better. I covered this topic at secondary, Bachelor and Master's level, so there is choice.

When deciding on what level to write for, I try to make an estimate of who is coming to Wikipedia for this topic, rather than where the topic is covered. I imagine those going a masters in this topic would have their textbooks for the gritty details. The bigger group would be a general audience, with a few undergraduates. I think a large part of the article should serve them. Femke (alt) (talk) 16:50, 2 June 2023 (UTC)

User:Rhwentworth In your /* Addressing misconceptions */ section, I see terms that I as an engineer have a vague grasp of and can somewhat distinguish from each other, but I definitely don't think college freshman would be able to readily appreciate or clearly distinguish: "radiation heat transfer", "radiation heat flow", "radiation heat transport", "radiative energy", "thermal radiation", "thermal energy", "radiative surface cooling", "latent heat transport", "thermals (conduction and convection)". Definitely, to understand the narrative here, college students (especially non-physics majors) would have to first study at length the internal links to those other concepts before returning here to assimilate the GHE process in their minds. That is why I have suggested that the exhaustively detailed technical details could be recited in a new sub-article that is linked from here. WP:ONEDOWN should be applied to both this article and the new sub-article. —RCraig09 (talk) 18:16, 2 June 2023 (UTC)

Thanks for the feedback. I'm thinking about how to simplify (or provide background for) what is said about thermal radiation vs. radiation heat flow so that it's more accessible. These issues are sufficiently important to understanding what is going on physically that it's probably worth trying to find a way to get it right while being clearer, rather than just taking it out. It may take some time for me to find time to sort this out, but it's on my to-do list. Rhwentworth (talk) 06:01, 6 June 2023 (UTC)

Thanks for the feedback concerning reading level. Makes sense to me. I think that's what I've been aiming for, but your summary will help me keep my eye on that. Rhwentworth (talk) 06:37, 6 June 2023 (UTC)

Proposed GHG molecule I/O (input/output) diagram

In the diagrams being discussed and added in recent weeks, GHGs are always "in the background"--yet they're at the center of the GHE. Would anyone (especially User:Rhwentworth) consider creating a ~simple energy flow diagram that shows the energy inputs and the energy outputs of a single GHG molecule, shown with respective incoming arrows and outgoing arrows? (I picture something similar to the structure of the first diagram on this page.) Such a ~simple energy flow diagram might help to pull together how the GHE operates, because recently created diagrams require considerable study to begin to appreciate. I don't understand the subtleties well enough to even attempt. If this is a bad idea, feel free to ignore! —RCraig09 (talk) 03:09, 4 June 2023 (UTC)

It's a stimulating suggestion. My first thought is that I don't think anything interesting or supportive of insight happens at the level of an individual molecule. (Maybe I'll change my mind after more consideration. I'd need a clearer motivation for why we would want to include a figure at that level. Maybe a boring figure at that level would be useful at debunking false beliefs that something exotic is going on at that level? What do you imagine happens at that level?)

Interesting things happen at the level of either a thin layer of the atmosphere, or more so at the level of looking how things evolve as you move upward through the atmosphere. (For an example of the latter, as you move upward, the upward thermal radiation energy flux decreases but the upward radiative net heat flux increases. Changes in the downward thermal radiation flux account for the difference. I've got references to support this, and ideas about presentation.)

I think there is potential to adapt some of the figures I've seen to something that would be reasonably clear and useful. Rhwentworth (talk) 06:19, 6 June 2023 (UTC)

— I was just thinking of an octopus-looking (or starburst) diagram with arrows pointing into and out of (and maybe through) a central hub that is the GHG molecule. The arrows could have appropriate labels along the lines of... "radiation heat transfer", "radiation heat flow", "radiation heat transport", "radiative energy", "thermal radiation", "thermal energy", "latent heat transport", "thermals (conduction and convection)", etc.—whatever is most correct, keeping in mind conservation of energy but showing any imbalances that illustrate what's special about GHGs that underlie the GHE. —RCraig09 (talk) 15:45, 6 June 2023 (UTC)

— ... but when you write "the upward thermal radiation energy flux decreases but the upward radiative net heat flux increases", I think you'll lose >95% of readers. You're used to talking with other physics PhDs. I think the terms I listed in my 15:45 post would need to be simplified to the level of an inquisitive high school graduate who reads further than the lead. I realize that wording simplification is a challenge. —RCraig09 (talk) 16:03, 6 June 2023 (UTC)

Heat flow profile of Earth's atmosphere, showing (a) radiative cooling and thermal radiation fluxes, (b) non-radiative heat flow, (c) balance of atmospheric heating and cooling, and (d) temperature profile.

I think it will become considerably easier to explain what is meant about thermal radiation and radiative heat flow using this new figure.

I'll think about whether there could be a complementary figure that would show things at the level of a thin layer of the atmosphere (or possibly at the level of a GHG molecule). But first, I'll need to recover from the substantial effort of generating this figure (albeit based on a great resource I found), and then work on simplifying text in the section you're concerned about. Rhwentworth (talk) 07:23, 7 June 2023 (UTC)

Over time, I've been gaining a sense (still not a deep understanding) of how the GHE works. File:Atmospheric_heat_flow_profile.svg is a well organized diagram. By way of feedback, I think the major step forward in communicating with non-physics-PhDs is to simplify language—to distinguish in layman's language the various terms in the diagram—remove jargon while still remaining technically accurate. —RCraig09 (talk) 13:31, 7 June 2023 (UTC)

Examples (verify for precision):

1. "Heat flow profile of atmosphere" --> "Flow of heat in the atmosphere"
2. "radiation heat flow upward" --> "radiant heat" with an up-arrow
3. "downward thermal radiation" --> "radiant heat" with a down-arrow
4. "decrease in upward thermal radiation" --> "reduction in radiant heat going to space"
5. "latent heat and thermals" --> "heat flowing through physical contact and motion" with up-arrow
6. also: small left-arrowhead near "cooling' and small right-arrowhead near "warming"

—RCraig09 (talk) 16:58, 7 June 2023 (UTC)

Good graphic, although it won't be easy to view on smartphone and thumbnail. It could be good for more advanced articles where people are honestly trying to learn, although I don't think it will help in convincing ghe deniers. Things I find confusing:

1. I am suspicious of how a and b are smooth lines, while graph c shows a lot of variance by altitude. Are a and b based on real data measured at various altitudes, or are they extrapolation based on just 2 or 3 data points?
2. The third graph doesn't include any greenhouse effect impacts on temperature, I'm not sure why. Shouldn't absorption of radiated heat be a warming input?
3. For graph a, I could see a denier getting confused by how radiation heat flow upwards is smaller than downward thermal radiation, thinking that violates the second law of thermodynamics

Overall, I confess that I find the data interesting, but not really enlightening in terms of forming a mental model. What I'd most like is 2 graphs side by side, where one shows heat flow or temperature in the atmosphere by altitude without greenhouse gases, the other showing the same thing with greenhouse gases. Efbrazil (talk) 15:44, 7 June 2023 (UTC)

If the actual GHE itself can't be illustrated, then I agree with Efbrazil that a side-by-side, with-and-without-GHG comparison is also needed. —RCraig09 (talk) 17:01, 7 June 2023 (UTC)

I understand Efbrazil's concern that the left panel is over-simplified, but I think that such simplifications are what is/are needed in a high-level article. Panel (c) might even be purposely simpified for this reason. A small legend could say "Renderings are simplified for illustration". —RCraig09 (talk) 17:09, 7 June 2023 (UTC)

@RCraig09 I will look into adding some arrows as appropriate. Your language which is intended to simplify actually makes clarity much more difficult. You're proposing referring to "thermal radiation" as "radiant heat", yet the main distinction that is helpful to get is that "thermal radiation" is NOT heat. Your suggestion would confuse that issue. One simplification I have made is to try to consistently use the same phrases, rather than varying the wording different times that a concept is referred to. I can probably implement the suggestion of refraining from using the word "profile." (It means that we are talking about variation with altitude, as oppose to transverse variations, but I suppose it is ok for that to go unsaid in this context.)

@Efbrazil

1. (a), (b), (c) and (d) are all from the same data-set and are mutually consistent. Chart (c) shows the derivative with respect to height (with an added adjustment related to density) of the curves in (a) and (b), which is why it is a bit jagged while (a) and (b) are smooth. I agree that this point might be confusing. The jaggedness is likely a numerical artifact rather than a real phenomenon. So, I will look into artificially smoothing the jaggedness in (c), consistent with what RCraig09 suggested.
2. In principle, I could add an "absorption" curve on the right in (c) and an "emissions" curve on the left. That would (i) complicate the diagram, and (ii) change the scale so that latent heat and solar warming would be dwarfed to insignificance in comparison. Instead, I've chosen to show the "net effect of absorption and emission". Perhaps it would be helpful to add a label to that effect? Contrary to your lead-in to this point, I don't see any sense in which this would be a "greenhouse effect impact on temperature" even if it was included. It's more an example of a misconception about how the greenhouse effect functions (albeit not clear enough to be worth addressing in the article).
3. There are endless opportunities for deniers to misunderstand anything that is said or shown. I believe that any confusion about radiation down being larger than heat up (but not radiation up) is a second-order issue, less significant the the primary confusion (a failure to distinguish heat and radiation) that the diagram is trying to help clarify. I don't see a way of heading off this possible confusion without adding unnecessary complication that would increase rather than decrease confusion.

The current diagram has a purpose of illuminating certain specific misconceptions. It doesn't have a primary purpose of explaining how the greenhouse effect makes things warmer. A separate diagram would likely be helpful for that, although it could use components of the current diagram, e.g., chart (a). I agree that a side-by-side comparison would likely be useful. (I'm somewhat amused by the suggestion, insofar as in earlier discussions I proposed side-by-side comparisons and you continually objected that such comparison was unnecessary. But, perhaps the context is now different.)

Thanks for the feedback. I'll add some "to-do" tasks to my list. Rhwentworth (talk) 18:55, 7 June 2023 (UTC)

Thanks, User:Rhwentworth, for clarifying the misunderstandings in my verify-for-precision suggestions above; I do think a simpler term for "thermal radiation" is needed, making it understandable in a high-level article. Yes, the context is different: explaining the GHE in general versus showing energy flow more specifically. —RCraig09 (talk) 19:07, 7 June 2023 (UTC)

I've updated the diagram, with numerical artifacts smoothed away, arrows, etc.

Standard alternatives to "thermal radiation" include "longwave radiation", "terrestrial radiation", "thermal infrared", or longer combinations of these words. If you try to use something "friendlier" than that, you risk using non-standard language and being vague or technically wrong. I started out not liking "thermal radiation", but Efbrazil was arguing for it at one point as being widely used, and the term has grown on me.

"Latent heat" could be called "phase change" -- or "evaporation/condensation" or "evaporation" in the context of the surface or (perhaps) "condensation" in the context of the atmosphere. I've used "evaporation" in other contexts, when focused on heat flow at the surface. In this context... I don't see the alternatives to "latent heat" as being better. None of the options seems likely to be understood without explanation. And, given that an explanation is available, it's useful for people to learn the term "latent heat" because it is a concise very standard term with a well-defined meaning. ("Latent heat" is currently defined in article, near where the figure appears.)

I'm amused that you distinguish "the GHE in general versus showing energy flow more specifically", since the only explanations of the GHE that I'm aware of are either terminally vague or involve energy flows. Rhwentworth (talk) 00:33, 8 June 2023 (UTC)

Thanks! For this chart, I see value in graphs A and D but not graphs B and C in describing the GHE. For the GHE we should be focused on thermal radiation, but you dismiss it by saying that absorption and emission are offsetting. However, the same could be said for sunlight- all the heat the planet absorbs from the sun it radiates outwards, it's just that it partitions into different forms in the atmosphere, and that's all that graph B and C talk about.

Graphs A and D are somewhat useful for describing how the GHE raises temperature. Graph C could be cut or changed to only focused on thermal radiation, and instead of having offsetting warming and cooling it could just be a graph showing thermal radiation activity by altitude (where activity is rate of emission + absorption). Efbrazil (talk) 17:36, 8 June 2023 (UTC)

You are ignoring the context of what this particular chart, File:Atmospheric heat flow profile.svg, was created for. It was not created to illustrate how the GHE causes warming. It is meant to accompany the discussion of misconceptions about the effects of GHGs. Chart (c) supports discussion of a misconception that GHG's "warm the air"—something that they do not do, except very indirectly (at the level of whole-planet equilibrium). What actually happens is that non-radiative heat sources and sunlight heat the air, and GHGs cool the air. Chart (c) addresses the specific purpose of illustrating that fact. Chart (b) exists to help support understanding of chart (c).

Your comment seems to be about what should or should not be in a different figure which would exist to support understanding of how the GHE warms the planet.

You questioned why I would seem uninterested in the partition between emission and absorption, when I am bothering to plot the partition between energy from sunlight and non-radiative heat flow vs. radiative heat flow. The difference I see is one of one of what moves energy from place to place. Sunlight and non-radiative heat flow move energy between different locations in the atmosphere. In contrast, it is only the net effect of emission and absorption that is involved in moving energy between different locations in the atmosphere.

Even if it were meaningful, a plot of "thermal activity by altitude" would be difficult to present in a meaningful way. If one plotted "rate of emission" and "rate of absorption" as separate curves, those two curves would be visually indistinguishable. They differ by perhaps 1 percent. That's why chart (c) only shows the difference between those two curves, as a "net effect."

You seem to have some ideas about how greenhouse effect warming happens, ones which you would like to see illustrated? However, you are not being explicit enough about your reasoning for me to be able to know what you mean. So far, I don't see why you would want the plot you are suggesting. Could you explain in what way you believe such a plot (if only it were possible present effectively) might be meaningful? Rhwentworth (talk) 20:33, 8 June 2023 (UTC)

"Thermal infrared" vs. "thermal radiation"

@RCraig09@Efbrazil: I am wondering if it might make sense to prefer using the term "thermal infrared" instead of the term "thermal radiation", as our term for consistently referring to this phenomenon? Here are some arguments in favor of this possible change:

1. The term "infrared" is familiar to many people. Perhaps "thermal infrared" would seem less unfamiliar/mysterious than the term "thermal radiation"?
2. The term "thermal radiation" is not one of the equivalent terms listed by the IPCC in their glossary. That glossary lists as equivalent terms longwave radiation, thermal infrared, and terrestrial radiation. Among those choices, I think "terrestrial radiation" is too long, and "longwave radiation" is less intuitively meaningful than "thermal infrared".
3. Although some sources use the term "thermal radiation" in the way that we've been using it, technically the term Thermal radiation refers to any radiation emitted as a result of temperature; thus, sunlight is also "thermal radiation." So, our usage of the term to mean only longwave thermal radiation is technically inaccurate. I suspect that is why the IPCC does not include the term in their list of synonyms. You need an additional qualifier to make the term accurate. Thus, "thermal infrared radiation" or "infrared thermal radiation" or "longwave thermal radiation" are technically correct, if verbose.
4. When one says "infrared", arguably "radiation" is implicit, so perhaps we can omit the the word "radiation". That serves conciseness, and perhaps reduces mention of "radiation", which others has argued to be an off-putting term.

I'm not committed to this being a necessary change, but I wonder if it might help. Thoughts?

AFTERTHOUGHT: Since the word "thermal" distinguishes longwave from shortwave radiation only in informal usage, I'm realizing that "thermal infrared" is no more technically correct than is the term "thermal radiation." So, this issue is really only one of which term might be more comfortable for article readers to encounter.

Avoiding talking about this phenomenon altogether is not a viable option within an article about the greenhouse effect; it's the phenomenon that the greenhouse effect depends on and is all about. So, readers fundamentally need to learn this concept, if they are going to do more than glance at the article. The article does define this concept, and offers synonyms, in the section "Longwave vs. shortwave radiation." Rhwentworth (talk) 22:38, 8 June 2023 (UTC)

As an expedient, is it proper to use "infrared" by itself? It's a common word for non-techies. ("Radiation" invokes thoughts of Hiroshima, Chernobyl, and Star Trek.) —RCraig09 (talk) 02:40, 9 June 2023 (UTC)

My preference is thermal radiation or longwave radiation. We have to explain radiation to differentiate from other types of heat transfer, and then we need to clarify the type of radiation to distinguish it from sunlight. I don't like just infrared on its own and it's inaccurate, and I expect most people visiting the article also won't know what infrared means.

I also think it's good for us to be consistent and use the same term everywhere. It takes some explaining to define the term, so we shouldn't confuse things by popping around between different terms. Efbrazil (talk) 18:09, 9 June 2023 (UTC)

I'm all for consistency of terms. Choose the correct term that is the least jargony, and explain any jargony term upon its first usage, rather than merely wiki-liking to it. —RCraig09 (talk) 21:34, 9 June 2023 (UTC)

@RCraig09 You seem to be repeatedly admonishing us to "Choose the correct term that is the least jargony, and explain any jargony term upon its first usage, rather than merely wiki-liking to it" — yet it appears to me that we are already generally doing that.

In most cases where we wiki-link something, it is also explained somewhere nearby. I'm happy to have you point out any exceptions to that.

We explain the term "thermal radiation" in more than one place. (Wiki-linking the term "thermal radiation" is actually problematic, because the link takes one to an article which reveals that "thermal radiation" is in general not limited to being longwave infrared radiation.)

On balance, "thermal radiation" currently feels like the "least jargony" alternative we have.

"Longwave radiation" is more technically correct, and is what I see most used in the technical literature. Also, it's referred to in terms like "outgoing longwave radiation" (OLR). So, there could be an argument for switching to that, to ensure full consistency. I'd be willing to switch to "longwave radiation" if others supported the idea. But it's probably (?) less friendly-sounding and intuitive than "thermal radiation"? Rhwentworth (talk) 20:14, 10 June 2023 (UTC)

Apologies: I've intended it as a goal, not an admonishment of failure. I was hoping the article would flow more smoothly for lay readers who would read the article sequentially, wanting to minimize side trips to other articles. I think one subsidiary article is best for most of the 50% growth this article has seen (I will discuss below today or Sunday). —RCraig09 (talk) 22:22, 10 June 2023 (UTC)

On terminology: Britannica's GHE article uses "infrared radiation". —RCraig09 (talk) 15:50, 11 June 2023 (UTC)

While some people refer to "infrared radiation" when talking about the greenhouse effect, this tends to contribute to confusion. A greenhouse effect denier will say "They say greenhouse gases let sunlight through but absorb infrared, but sunlight is 49% infrared, so they are wrong—greenhouse gases absorb sunlight." The bit about sunlight being 49% infrared is correct, but the idea that this means greenhouse gases absorb that infrared is wrong. This false logic even made it into a flawed scientific journal article that somehow got published.

I think it's important to use a term that distinguishes what we are talking about from sunlight, and the term "infrared radiation" doesn't do that. Rhwentworth (talk) 18:51, 11 June 2023 (UTC)

I am consolidating the article to longwave radiation. It works best as a general term for several reasons:

• A key concept is outgoing longwave radiation
• Infrared radiation is inaccurate as you really need to say far infrared
• Thermal radiation can mean all temperatures so it isn't accurate without qualifications
• It's a good counterpoint to shortwave radiation or solar radiation, which I think we can use interchangeably

Efbrazil (talk) 18:59, 20 June 2023 (UTC)

Suggestion: [[Physics Scientific principles underlying the greenhouse effect]]

Step back from this process and take pause. In both graphics and textual explanations, we seem to agree it's hard ("tricky") to convey the GHE to lay readers.

I perceive that this article's 72-->108 KB (50%) growth in length since late March, and its dizzying increase in complexity, are hurting, not helping, that readership. Much of what has been recently added overcomes subtle technical misconceptions that lay readers couldn't possibly have had the depth of understanding to suffer from, in the first place. Many additions are essay-like constructions, and may violate WP:SYNTH, as briefly discussed above.

In this high-level article with almost 1500 views/day (almost half of Climate change's views), the IPCC definition could be presented, and then explained in layman's terms in a few hundred words. If a jargon term is necessary, it should be explained at its first usage and not merely wiki-linked. Such an approach had been basically accomplished in the /*Definition*/ and /*Principles*/ sections in the ~March version. The lead has already been ~successfully adapted to a broad readership in a similar manner.

In contrast, subtle distinctions or lengthy technical embellishments requiring even technical readers to study concepts in other technical articles, should be placed in a subsidiary article that would of course be linked from this article. Suggestion: Physics (Physical?) principles underlying the greenhouse effect. I hope we don't lose sight of the fact that this article is for its readers. —RCraig09 (talk) 03:15, 9 June 2023 (UTC)

I can conceive of splitting off a separate Physics of the greenhouse effect article. There are, no doubt, different categories of readers who would be served by material at different levels. I hope we don't lose sight of the fact that not all readers have the same needs.

You and I apparently have very different opinions of the article as it was in late March. I assess that as being a surprisingly low-quality article for such an important topic. The coverage seems uneven in level and lacking in insight, editorial balance, and overall coherence. If I wanted someone to learn about the greenhouse effect, I would not be comfortable referring them to that, no matter what their educational level might be.

So, if the article was split up, the main article would still need a lot of work, in my view. Rhwentworth (talk) 09:06, 9 June 2023 (UTC)

Certainly the quality, including balance and consistency, of the March version could be improved. My 03:15 post mainly concerned the technical level of this high level (~1500 views/day) article. Certainly this article isn't being visited by 1500 physics majors per day. Article quality could have been improved in the same manner the lead quality has been improved, without increasing size with exhaustive technical minutiae. What's left now is largely impenetrable to >95% of readers. —RCraig09 (talk) 15:01, 9 June 2023 (UTC)

As an alternative to creating a separate article, perhaps we could divide the article into an initial "Non-technical overview" section and a "Technical information" section? Perhaps that would help the article serve multiple readerships? Rhwentworth (talk) 20:57, 10 June 2023 (UTC)

Let me elaborate on the suggestion.

Currently, most sections of the article after the "History" section offer a mix of non-technical and technical information. This was true even before I began editing. Trying to have individual paragraphs be both understandable to non-technical readers and useful to technically-knowledgeable readers likely poorly serves both audiences. So, covering topics at both a non-technical level and a technical level, and doing so separately, could potentially better serve both audiences.

This could be done be creating a separate Greenhouse effect (technical) article. However, moving towards separating the content within the current article would be a less drastic, more incremental step. So, I think it would be preferable.

Even if a separate Greenhouse effect (technical) article was eventually split off, starting out by simply partitioning the current article would help making any eventual two articles more mutually consistent and coherent.

I could envision an initial outline something like the following:

1. History
2. Non-technical overview
   1. Definition
   2. Principles, etc. (this would likely take more than one subsection, even at a non-technical level)
   3. Atmospheric components
   4. Role in climate change
   5. Bodies other than Earth (might just say that there is an effect on Venus, Mars, and Titan)
3. Technical definition (currently called "as a measurable quantity)

This would then be followed by the other current sections, initially largely as-is.

Conceptually, I'd ideally want to put the later sections in an overall "technical information section." However, that would hamper readability and navigation, because Wikipedia formatting doesn't provide easy visual distinctions between 2nd and 3rd level subsections. The technical material benefits from being broken up into subsections, to organize the material.

The subsections of the "Non-technical overview" would provide whatever can be conveyed without getting too technical. Material that requires more background would be in the later sections, available to more motivated readers and more knowledgeable readers.

Thoughts? Rhwentworth (talk) 23:36, 10 June 2023 (UTC)

— I think strongly that the ultra-techy details need a separate article. The "dramatic change" you refer to has already occurred: the number of Sections+Subsections has grown from 13 in the March version to 35 today, while the article byte length has increased by 50%.

— Much of the new content doesn't merely describe the GHE itself (as expected in an encyclopedia), but also why it works this way and not that way, and sometimes argues against misconceptions some people might have. It's like a technical essay—sometimes with something to prove—not an encyclopedia article. It's too much. Please take a moment to look at Britannica's GHE article. This is what ordinary people read. (P.S. Britannica uses "infrared radiation".)

— I agree that "covering topics at both a non-technical level and a technical level, and doing so separately" would indeed serve both laymen and experts. Beginning as early as /*As a measurable quantity*/, the text already dives somewhat densly into formulas, techy terms, and the dreaded Greek letters. To keep both layman's text and techy diversions in the same article would probably balloon the number of (sub)sections even further. It's dizzying to survey this article as it is. Also, an illustration is supposed to be illustrative (ideally not requiring explanations outside the illustration itself), so any complicated diagrams should migrate to the subsidiary article.

— For these reasons, I think it would be best if you remove much of the May-June content and create a new article with a suitable title like Physics of the greenhouse effect and then edit it, Warp 10 if you like. You could edit (not so much expand) the present article so it's consistent with the techy details without delving into the techy details. One test: Ask your Amazon guy or bowling buddy to look at it for a few moments, and see the reaction.

— FYI Re article naming: In the huge ~2019 Global warming --> Climate change + Climate variability and change renaming discussion (skirmish, actually), parenthetic phrases in titles were discussed and discarded. On Wikipedia, parenthetic phrases in titles are almost always used to disambiguate different things that have the same name, as in Mercury (element), Mercury (planet) and Mercury (mythology). To name something Greenhouse effect (technical) would imply the main article Greenhouse effect is about a different subject, which it's not.

— I don't mean to discourage your contributions. I think it's a matter of appropriateness for the lay audience of a general encyclopedia. —RCraig09 (talk) 04:05, 11 June 2023 (UTC)

It's not generically true that all Wikipedia articles are, or should be, non-technical. Many Wikipedia articles cover topics that are inherently technical, and those articles often delve extensively into technical details, including equations, greek symbols, specialized mathematical symbols, technical jargon, and so on. The technical content in the current "greenhouse effect" article is much less technical than the content in many Wikipedia articles I've read. (I do have a predilection for reading more technical articles.)

So, I wish you wouldn't make your arguments in a way that suggests that Wikipedia/encyclopedia articles should in general be at a particular level, or that Wikipedia readers are all served by a particular level of presentation.

It depends on the subject.

The greenhouse effect is somewhat unusual in that it is a subject that is ultimately inherently technical, yet also has a high level of interest from readers without a technical background. (In addition, in my experience, there is also a substantial middle-ground of readers with no technical background but who nonetheless want to understand the technical details of everything related to climate change.)

I hope we are in agreement that it would be desirable to find a way to serve well both non-technical and technical readers who are interested in the greenhouse effect?

# # #

The question is how to do so.

I'm not opposed to creating two separate articles.

However, as a matter of how to get from here to there, I would find it much more do-able and less stressful to apply an incremental approach.

Towards that end, I suggest following through with the suggestion to start by re-organizing the current article to separate and fill out non-technical and technical content. That would set things up for a graceful transition to having two separate articles. The alternative would be to first make two separate articles, then engage in a mad dash to clean up the mess that has been made in both articles are a result of the premature split. I don't relish such a process.

Are you willing for us to start with this, by creating an non-technical overview section that would be a container for the non-technical content?

# # #

I take your point, with regard to the convention for the use of parenthesis in article titles.

Previously, I thought a title like "Physics of the greenhouse effect" might work. However, reviewing the article (even as it was before I started editing), I see technical content throughout that isn't quite right for a non-technical reader, and the technical content isn't necessarily specifically about the physics. So, I'm wondering what an appropriate title would be. Maybe Technical aspects of the greenhouse effect? Seems a bit awkward, but generally points towards what is needed. Alternate ideas?

Perhaps an appropriate name might become more apparent once the non-technical and technical content of the current article has been separated? Rhwentworth (talk) 22:24, 11 June 2023 (UTC)

— I definitely don't think all Wikipedia articles should be non-technical. I expect formulas when I click on quantum physics. However, the present 1500 view/day article, which explains what underlies about the most pressing crisis for the planet, should be readily accessible for the general public at the level of Britannica's GHE article.

— Here, most of the recently added science will be largely impenetrable to the layman, who will have trouble understanding or seeing how the numerous sections interrelate. I show some of the new graphics below in hopes you will get an impression of how laymen—probably at least 90% of incoming readers—would soon be lost (even techies would find it challenging since this is not a formally "science encyclopedia"). The boundary between "non-techy" and "too techy" should result in this parent article being concise and without technical digressions and arguments and arguments that would be dizzying to laymen.

• 
• 
• 
• 
• 
• 
• 
• 
• 

— An encyclopedia article would normally describe what a subject is. However, here, some additions add different slants: why surface and outgoing fluxes differ, why the GHE doesn't work the way you suspect some think it might work, etc. That's where it resembles an essay, not an encyclopedia article. Tellingly, much of /*Addressing misconceptions*/ is vaguely sourced to entire books without specific pages or passages, which is WP:SYNTH essay-like (see WP:NOTESSAY), especially when apparently no source is cited to describe the italicized statements as misconceptions in the first place.

— Seeing your 22:24 comments, I suggest a title, Scientific principles underlying the greenhouse effect or similar, mentioning science rather than "technical..." which is often interchanged with technology.

— As you would be the one spearheading the work, I acquiesce in whatever process you choose, but the results should hopefully be the same. —RCraig09 (talk) 04:41, 12 June 2023 (UTC)

How about Science of the greenhouse effect as a title? Rhwentworth (talk) 00:17, 13 June 2023 (UTC)

— FYI: The quantum physics article has subsidiary articles, Mathematical formulation of quantum mechanics and Applications of quantum mechanics. —RCraig09 (talk) 04:45, 12 June 2023 (UTC)

Agree in general.

"misconceptions" could go in an FAQ page, as we did for climate change. See here: https://en.wikipedia.org/wiki/Talk:Climate_change/FAQ

After that, I don't know that a separate article is necessary. Climate change is 9687 words, this article is now 7480 words, so length isn't the key issue. The issue is complexity of concepts. The lead should always be accessible to a middle schooler or anyone completely unfamiliar with the material and looking only at their smartphone. I'd try to maintain that standard through the first half of the article if possible. Articles can be more advanced towards the end.

I think what I'd do is try to reorganize the article by complexity, with mathy stuff and advanced graphics at the end in a clearly labeled more advanced section (maybe "Physics of the greenhouse effect"). That particularly means pulling mathy stuff out of "As a measurable quantity", "Greenhouse effect and temperature", and "Radiative balance".

I could take a crack at that unless Rhwentworth does first. Efbrazil (talk) 17:36, 13 June 2023 (UTC)

Good point re taking "misconceptions" to the Talk Page. Moving the hairy-thermodynamics-content down is the least one should do in a general-audience encyclopedia, but if it's done smoothly, with the audience constantly in mind, I could acquiesce. Since the CC article is one of the most important articles on the entire website, I don't think a Kbyte-size comparison to CC is appropriate; something more like the way quantum physics article has subsidiary articles Mathematical formulation of quantum mechanics and Applications of quantum mechanics is appropriate. —RCraig09 (talk) 19:51, 13 June 2023 (UTC)

I'm working on the transition to separating less technical and more technical material. I expect it to be an iterative process. First steps will be coming soon, but that won't be the final state. Rhwentworth (talk) 22:13, 13 June 2023 (UTC)

Things are looking signficantly better now, thanks! I very much like having the greek letters sequestered to one section. Let us know when you're getting close to being done editing and I will go over things in more detail. We might also want to tighten things up, maybe by trimming down the greenhouse gases section, since there's already an article clearly dedicated to that topic. Efbrazil (talk) 16:12, 15 June 2023 (UTC)

I'm done with major edits for the moment. I trimmed the greenhouse gas section. Rhwentworth (talk) 04:16, 17 June 2023 (UTC)

Thanks! Pinging User:RCraig09 as a heads up. Efbrazil (talk) 02:38, 18 June 2023 (UTC)

Merci bien for le ping. User:Efbrazil User:Rhwentworth Because the /*Definition*/ section closely follows the lead and /*History*/ sections, I've just boldly condensed and re-organized and simplified it for the lay reader, re-naming it /*Measurement*/ because that's what almost all of the content pertained to. I purposely omitted the bodaciously-scary-to-the-common-man-but-not-adequately-explained-afterward IPCC definition as being more appropriate to the techy sections below. —RCraig09 (talk) 04:15, 18 June 2023 (UTC)

I took a readability pass down to the point of "greenhouse gases", will hopefully continue tomorrow. Efbrazil (talk) 19:19, 20 June 2023 (UTC)

Suggested rewrite of first paragraph

The first sentence is good, but the second sentence and what follows doesn't flow from the first sentence- it reads like a completely separate paragraph. That makes the whole thing hard to read.

We also neglect to mention how starlight is shortwave radiation in contrast to longwave radiation from the planet. I think that's good to clarify as that's the key property of greenhouse gases- they allow shortwave through but block longwave. Without saying that, we are allowing confusion to new readers, for instance they could think light is not radiation. Here's a suggested rewrite:

The greenhouse effect occurs when greenhouse gases in a planet's atmosphere cause some of the heat radiated from the planet's surface to build up at the planet's surface. This process happens because stars emit shortwave radiation that passes through greenhouse gases, but planets emit longwave radiation that is partly absorbed by greenhouse gases. That difference reduces the rate at which a planet can cool off in response to being warmed by its host star. Adding to greenhouse gases further reduces the rate a planet emits radiation to space, raising its average surface temperature. Efbrazil (talk) 17:28, 27 June 2023 (UTC)

Overall I think it's a definite improvement. I've long perceived that the present intro digresses to explain some underlying background principles. Your suggestion overcomes that awkwardness by describing the GHE in a single progression of concepts. Minor observations:

1. First sentence: We've had discussions as to whether it's truly "heat" that's radiated from a planet's surfact.
2. "This..." (alone) isn't a good subject of a sentence, grammatically. Maybe "This phenomenon..." or "This process..." could be used (two instances of "This..." occur).
3. The second phrase of the second sentence seems to imply that GHGs absorb all LW radiation.

—RCraig09 (talk) 19:59, 27 June 2023 (UTC)

Thanks! Changes made inline above:

1. I'm fine with the first sentence as is, or at least nothing better occurs to me.
2. Changed the first "this" to "this process". The second "this" is changed to "that difference".
3. Added "partly"

Additionally, I added "to space" to the last sentence as a clarification

—Efbrazil (talk) 20:27, 27 June 2023 (UTC)

Done, with minor tweak (can emit --> emits in last sentence).

—Efbrazil (talk) 16:19, 28 June 2023 (UTC)

I also changed the third paragraph and swapped it with the fourth paragraph as I noticed that the first paragraph rewrite overlapped with it. It now covers new territory, but the basic idea is the same- to further ground the physics that the first paragraph introduces. I went live with the change because I think it was necessary to eliminate the redundancies. Efbrazil (talk) 17:49, 29 June 2023 (UTC)

As per your comment in the last article edit, I swapped the third and fourth paragraphs of the lead because the greenhouse paragraph introduces the idea of radiation and concludes with a sentence that transitions nicely into talking about radiation wavelengths. Having them the other way around there was no logical flow. Efbrazil (talk) 19:41, 29 June 2023 (UTC)

Ok, I'm out of ideas for now RCraig09. I understand the last 2 paragraphs of the lead are a bit awkward, but I think they are very valuable as a pathway to really understanding the basics of the greenhouse effect. I hate explanations that just say "trust the experts", and I also hate explanations that fall back on jargon and equations. Everything should be made clear and simple enough for someone to really understand what's going on. Let me know if you have further thoughts. Efbrazil (talk) 17:22, 30 June 2023 (UTC)

What I wrote in my 29 June edit comment to the main article was more an observation than a call to action. I think the lead can stay as is—subject to periodic improvements ;-). —RCraig09 (talk) 06:12, 1 July 2023 (UTC)

Confusing claim that "Greenhouse gases cool the air, since they emit more radiation than they absorb"

Text in "Radiative effects" section said: Greenhouse gases cool the air, since they emit more radiation than they absorb. Air is warmed by latent heat (buoyant water vapor condensing into water droplets and releasing heat), thermals (warm air rising from below), and by sunlight being absorbed in the atmosphere. Warming from these sources supplies the energy which allows greenhouse gases to emit more radiation than they absorb.

First, it is confusing to lead with "Greenhouse gases cool the air", but that can be fixed with wording. More substantially, I don't know that the claim is correct for all greenhouse gases. Greenhouse gases that absorb longwave radiation will transfer energy to other molecules prior to it being emitted. Also, emissivity and absorptivity of a molecule can vary based on the wavelength of radiation, or temperature of the air. It all adds up to confusion for me, and it seems possible that there is a particular greenhouse gas at a particular atmospheric layer may take in more energy than it emits.

For now I simply omitted the information from the article, so that it now speaks in terms of the atmosphere as a whole. If there is a good source on the matter I'd like to see it. Efbrazil (talk) 18:03, 21 June 2023 (UTC)

This section may be related to the apparently-implausible statement that I questioned in the discussion leading to this diff: "GHGs emit more thermal radiation than they absorb". —RCraig09 (talk) 19:13, 21 June 2023 (UTC)

Yep, sounds like the same point. I believe what Rhwentworth is saying is generally correct- that the air is heated by ways other than radiation (including convection and phase change), whereas it cools only through radiation. Therefor, on balance, the atmosphere emits more radiation than it absorbs.

However, where I get fuzzy is in the absorptivity vs emissivity of specific gas types. It may be correct for all greenhouse gas types, but I couldn't find supporting documentation of that claim. Efbrazil (talk) 20:00, 21 June 2023 (UTC)

The references that were cited in the article in connection with that claim do support the claim. One reference is a textbook, which I have, but which is admittedly not very accessible to those without a copy of the book. The other reference is the journal article Manabe (1964). See figure 8b, which shows the longwave and shortwave effects of different gases as different altitudes.

As can be seen from that figure, the longwave effect is almost always a net cooling effect—and the effect is uniformly a cooling effect within the troposphere.

The only modest exception is in the case of ozone, which has a slight longwave warming effect in the stratosphere. That anomaly is a result of the concentration of ozone being dramatically higher at those altitudes; the ozone layer absorbs thermal radiation from below that wasn't being absorbed at lower altitudes, resulting in modest warming via absorption of longwave radiation. Note that the scale of the chart is temperature change, not energy. At high altitudes, it takes very little energy to heat or cool the thin gas. So, that ozone longwave heating effect is a very small effect if one considers its effect on energy flow.

All that business about ozone is at a much finer level of detail than the general level of discussion in the article. So, I don't think there is any need to go into those details. We can simply go with wording similar to what was being said, i.e., "Greenhouse gases cool the air, since they emit more radiation than they absorb." If necessary, we can add a qualifier, e.g., "they generally emit more radiation..." or "...in the troposphere" or something like that. But, as a broad statement, the words are pretty accurate even without a qualifier. Rhwentworth (talk) 21:54, 8 July 2023 (UTC)

Took out section on real greenhouses

I don't think that this section on real greenhouses is still needed in this article now. I've moved a small part of it to the "terminology" section. If someone wants to read up on real greenhouses, they can click on the hyperlink there. It is not the purpose of this article to explain how a real greenhouse works (my opinion). Here is the text that I deleted:

+++++++++

Real greenhouses:

A modern greenhouse in RHS Wisley

A greenhouse is built of any material that passes sunlight: usually glass or plastic. The sun warms the ground and contents inside just like the outside, and these then warm the air. Outside, the warm air near the surface rises and mixes with cooler air aloft, keeping the temperature lower than inside, where the air continues to heat up because it is confined within the greenhouse. This can be demonstrated by opening a small window near the roof of a greenhouse: the temperature will drop considerably. It was demonstrated experimentally (R. W. Wood, 1909) that a (not heated) "greenhouse" with a cover of rock salt (which is transparent to infrared) heats up an enclosure similarly to one with a glass cover. Thus greenhouses work primarily by preventing convective cooling.

Heated greenhouses are yet another matter: as they have an internal source of heating, it is desirable to minimize the amount of heat leaking out by radiative cooling. This can be done through the use of adequate glazing.

It is possible in theory to build a greenhouse that lowers its thermal emissivity during dark hours; such a greenhouse would trap heat by two different physical mechanisms, combining multiple greenhouse effects, one of which more closely resembles the atmospheric mechanism, rendering the misnomer debate moot. EMsmile (talk) 22:14, 6 July 2023 (UTC)

References

EMsmile (talk) 22:14, 6 July 2023 (UTC)

In general, I think this is a good change structurally, but I don't think it is helpful to characterize it as a misnomer. The prior language in the lead did a better job of shedding light on how heat transfers. I'll look to make subsequent edits that fix the regressions I'm seeing. Efbrazil (talk) 15:09, 7 July 2023 (UTC)

Thanks, I like your changes to the terminology section a lot. So just to be sure I understand: this misnomer thing is/was a minority view and not worth mentioning here at all? Or could it be worth saying "some say it was a misnomer but others dispute this because..." (or not worth saying if it's got only tiny representation in the literature). EMsmile (talk) 18:06, 7 July 2023 (UTC)

Great! The general flow of the debate before is that the greenhouse analogy is not perfect but also not bad on an intuitive level. In either case the sun's heat is being retained. The thought was that it is better to clarify the analogy than it is to characterize it as wrong or a misnomer. Efbrazil (talk) 20:46, 7 July 2023 (UTC)

@EMsmile, @Efbrazil: I think the elimination of the section on real greenhouses is an improvement, particularly after the subsequent collaborative edits. Thanks. Rhwentworth (talk) 02:47, 9 July 2023 (UTC)

Caption for File:Greenhouse effect with energy flows shown by altitude.svg

We're in danger of some churn regarding the caption of File:Greenhouse effect with energy flows shown by altitude.svg in the lead-in to the article. So, let's try to sort it out here.

After my edit, the caption was: "Energy flows down from the sun and up from the Earth. Greenhouse gases intercept some of the thermal radiation emitted by the surface, preventing it from having a cooling effect. This causes surface temperatures to rise."

After an edit by @RCraig09 this became: "Energy flows down from the sun and up from the Earth. Greenhouse gases intercept some of the thermal radiation emitted by the surface, preventing it from escaping into space, thus causing surface temperatures to rise."

I had a very specific reason for writing "preventing it from having a cooling effect" rather than "preventing it from escaping into space":

• The grey triangle in the diagram shows the region where downward radiation cancels out upward radiation. This is the portion of the upward radiation that does not contribute to radiative heat transfer (net energy flow), i.e., does not contribute to radiative cooling.
• What is "prevented from escaping to space" is the portion of upward radiation to the right of of the 240 W/m², the heating due to absorbed sunlight. That quantity is not called out or clearly identified in the figure (which is okay, given the intention of the figure).

So, your wording change changes a reference that describes the grey triangle into a reference that describes something else (something depicted only implicitly), leaving it more of a mystery what the grey triangle really corresponds to.

While many viewers won't understand things well enough to differentiate the two ideas, my way of labeling things would be more technically correct, and could help a reader who is trying to really make sense out of the diagram.

So, I'd like to go back to my wording, or something close to it. Rhwentworth (talk) 03:13, 14 June 2023 (UTC)

File:Greenhouse effect with energy flows shown by altitude.svg

My (substantive) problem was with the wording "Greenhouse gases intercept some of the thermal radiation emitted by the surface, preventing it from having a cooling effect." The "it" is ambiguous, in context—not clearly referring to the GHGs or to thermal radiation. Further, adding the concept of "cooling effect" complicated the description unnecessarily (and confuses readers who arrive having heard only of global warming). If you have a substantive scientific understanding that supervenes, please go ahead and revise the caption (with your Amazon delivery guy in mind), but please be aware of the language issues involved. —RCraig09 (talk) 03:24, 14 June 2023 (UTC)

@Efbrazil: I'm worried that your July 5 edit to the caption of the flows-by-altitude graphic suggests that GHGs cause the entire 33°C temperature increase, and that the temperature numbers aren't accurate or consistent. Suggestion for last sentence: When greenhouse gases intercept radiation emitted by Earth's surface, they redirect it in random all directions and cause the heat to build up as shown, resulting in the current surface temperature s rising by to about 33 15 °C (91 59 °F).... Does this make more sense? —RCraig09 (talk) 06:32, 6 July 2023 (UTC)

The suggestion is true- it's a 33 C rise. From -18C to 15C. 15 - -18 = 33. Efbrazil (talk) 17:20, 6 July 2023 (UTC)

There are a few goals here:

• Not be redundant with the first caption or lead text
• Really speak to the diagram
• I think it's good to call out the 33 C rise, as that is what greenhouse gases are causing

So, to go back to your text, I'm fine with some of the edits. Maybe this rewrite works:

Energy flows coming down from the sun and up from the Earth and its atmosphere offset each other. The gray area shows greenhouse gases that have intercepted longwave radiation and are redirecting it in all directions, so there is no net flow. This trapped heat causes Earth's surface temperatures to rise by about 33 °C (91 °F). Efbrazil (talk) 18:26, 6 July 2023 (UTC)

Eek! The 18:26 proposal is radically different, and is much less intuitive for laymen. "Offset" is a conceptual abstraction that many laymen won't quickly understand or readily apply to the diagram. The language doesn't explain, "no net flow..." ... of what? (in laymen's terms) There is no antecedent in the caption for "This trapped heat". Most importantly, a 33 °C rise is not the same as a 91 °F rise. From the diagram, it looks like GHGs add 15, not 33, degrees. My 06:32 proposal sought to simplify the explanation of the diagram for a reader seeing it for the first time, and make the temperature figures accurate and consistent. —RCraig09 (talk) 19:05, 6 July 2023 (UTC)

I see what you mean about the conversion, I just fixed that on the live page, thanks for finding that (I needed to use c-change in the conversion template).

The wording you have up above is just a restatement of what is already said elsewhere in the lead. What I think we need to do is speak to the diagram itself. Let's look for a middle ground between what I wrote and what you wrote. How about this. It is clearly an image caption, it makes no sense without it, and doesn't restate information already in the diagram (like the temperature change):

Energy flows coming down from the sun and up from the Earth and its atmosphere cancel each other out. The gray area shows longwave radiation that is flowing in all directions after greenhouse gases have absorbed and redirected radiation emitted by Earth's surface. Efbrazil (talk) 20:14, 6 July 2023 (UTC)

The lead is almost 350 words long (too long for some!), and it's 100% OK, even preferable, to repeat the important parts of text in lead images and their captions (both lead text and lead images are supposed to summarize the topic). I've just made non-substantive changes to the actual caption, thinking it should retain temperature numbers—which in this case are in the diagram—and "closing the (conceptual) loop". Saying "energy flows" offset/cancel each other etc. is counterproductive because it seems to suggest to new readers (or those that only look at the pictures) that nothing could possibly cause the planet to warm. —RCraig09 (talk) 20:55, 6 July 2023 (UTC)

In my edits, I'm trying to channel some of what rhwentworth brought to the content, as they are not taking part in this edit process. I understand your concern about saying cancel out, and it only cancels out when in a steady state. I'm ok leaving the image caption as it currently is. Efbrazil (talk) 15:42, 7 July 2023 (UTC)

I'm not entirely enjoying the changes to the caption:

• Prior caption: Energy flows down from the sun and up from the Earth. Greenhouse gases intercept some of the longwave radiation emitted by the surface, preventing it from escaping into space, thus causing surface temperatures to rise.
• Current caption: Energy flows down from the sun and up from the Earth and its atmosphere. When greenhouse gases intercept radiation emitted by Earth's surface, they redirect it in all directions and cause heat to build up. This heating results in surface temperatures being about 33 °C (59 °F) warmer.

The narrative about "redirecting" radiation is a lousy, misleading, problematic narrative, even it's a widespread one.

I'm willing to tolerate a little use of this narrative, as a concession to how familiar it is. But, I'd prefer to avoid repeating this narrative any more than absolutely necessary, because I think it's a counter-productive way of thinking about things, producing more misunderstanding than understanding.

The narrative has already been offered in the caption to the first figure. I'd really like the narrative offered in the caption for the second figure to be a step towards something a little closer to the being scientifically accurate and meaningful.

The "redirection" of radiation narrative is problematic because:

1. It suggests a fictitious connection between absorption and emission of thermal radiation; in reality, absorption and emissions are actually independent processes which have very little to do with one another. There is little if any inherent relationship between the amount of radiation absorbed and the amount emitted, contrary to what the narrative suggests.
2. It emphasizes a way of thinking about energy flows that is easily misinterpreted as violating the 2nd Law of Thermodynamics (which says that heat only flows from warm to cold); resolving that misunderstanding requires making distinctions that most readers aren't up to making. So, it seems best to simply avoid that emphasizing that way of thinking about energy flows.
3. It encourages falling into the "surface budget fallacy" in which one focuses on energy flows at the surface, rather than energy balance at TOA. Focusing on energy flows at the surface is very tricky to get right, and leads to erroneous conclusions more often than not, which is why such a focus has been labelled a "fallacy." Focusing on TOA energy balance leads to reasoning which is simpler, more rigorous, and more reliably correct.

I prefer the prior wording because it avoids the 3 problems above, while being simple and correct.

# # #

Regarding the subject of energy flows "cancelling"... That seems like a useful concept to me. Energy levels and temperatures change only to the extent that there is incomplete cancellation:

• The Earth warms because the energy leaving is slightly less than the energy arriving.
• Radiative thermal energy moves upward only to the extent that the flow of upward longwave radiation is greater than the flow of downward longwave radiation. That's exactly what the figure depicts: the gray area is the upward flow of longwave radiation that is "cancelled" by a matching flow of downward longwave radiation; the blue area is the upward flow of longwave radiation with no matching/canceling/counter-balancing flow of downward longwave radiation.

You may or may not want to try to explain this to readers, but it's fundamental to what the figure is actually plotting. Rhwentworth (talk) 04:16, 9 July 2023 (UTC)

File:Greenhouse effect with energy flows shown by altitude.svg

Spending (by MS Word's tally) 458 words to explain what is wrong with a 48-word caption, shows an attempt to anticipate more possible misinterpretations along abstruse lines that >90% of readers will never be capable of distinguishing. Lead text and images are supposed to be summaries for a layman's understanding; here, they're backed up by a now-dizzying set of over a dozen overlapping-concept technical diagrams that only a tiny fraction of Wikipedia readers will ever bother to tackle. A specific, non-jargon solution of under ~50 words is definitely needed, preferably one that concisely explains what's behind global warming. —RCraig09 (talk) 05:02, 9 July 2023 (UTC)

Those words are intended to support my co-editors in having a better understanding of the topic they are editing. To my mind, the standards for that are different than the standards for what actually ends up in the article.

I disagree that these are merely "possible misinterpretations along abstruse lines." Rather, I perceive these as extremely common misinterpretations (which are all but inevitable if all one ever reads is that sort of "explanation").

The original caption ("Greenhouse gases intercept some of the longwave radiation emitted by the surface, preventing it from escaping into space, thus causing surface temperatures to rise.") was under 50 words, and to my mind is a more accurate explanation than the longer one that currently appears in the caption.

I'm merely asking that the initial explanations not double-down on repeating the same rather poor "explanation", but offer some diversity in a direction that points towards better explanations.

The "redirects radiation" explanation is ONLY a surface explanation; serious explanations don't tend to expand on that. I think the use of such superficial explanations which can't sustain close scrutiny is a factor in the level of greenhouse effect denial that exists.Rhwentworth (talk) 06:26, 9 July 2023 (UTC)

— I've made some changes to the caption, intended to avoid the technical reasons for "why" or "how" GHGs work, but still explaining "what" they do. I think they'll meet with everyone's approval.
— Separately: is it meaningful to ask what the temperature is at the left side of the blue shaft? (We know the right side is -18 °C; what about the left?). I know we don't want to explain that question in the caption, but I was wondering about where the left side of the gray triangle should intersect the horizontal axis. No long explanations are necessary; just confirm that the present diagram is correct. —RCraig09 (talk) 05:53, 12 July 2023 (UTC)

Thanks for making those changes to the text.

The point where the left side of the gray triangle intersects the horizontal axis is "close enough" to where it belongs for the diagram to serve its purpose.

Explanations you don't need:

• It was a deliberate choice to not indicate a temperature for the left side of the blue shaft, i.e., the left side of the diagram, because it is complicated to talk about. (Per discussion earlier on this page, one could make arguments for the label being -273, -270, or -239℃; including any of these values would require explanation that isn't really helpful to the main point of the diagram.) It's more meaningful to say that the left edge corresponds to ~0 W/m². Deviations from exactly zero are why there is some ambiguity to the temperature there.
• The left side of the gray triangle doesn't correspond to a temperature in any way that is physically meaningful. That intersection point does correspond to a meaningful energy flux value. But, that value isn't worth explaining to readers. (The value depicted in the diagram, ~80 W/m², is a bit higher than the real global average, 56 W/m², but does correspond to a value that would exist in certain scenarios, and was the output of a particular climate model. So, the diagram as drawn is good enough to serve its intended purpose.)

Rhwentworth (talk) 18:11, 12 July 2023 (UTC)

How to organize explanations (reverted changes leading to "Modeling atmospheric layers")

I reverted two changes by @Efbrazil that led to a section being labeled "Modeling atmospheric layers." Those changes resulted in a wildly inappropriate section heading, and, to my mind, damaged the logical flow of the sequence of ideas:

• Most of the material in the section that ended up with the label "Modeling atmospheric layers" had little if anything to do with atmospheric layers, at most mentioning the a "layer" as something purely conceptual and incidental to expressing some primary idea. None of the material in the section describes "modeling" of layers. Modeling the atmosphere using discrete layers is a distinct thing in climate modeling, and the contents ended up under that heading have very little to do with that sort of modeling.
• The changes moved some text labels "Reduced heat loss" into a position of introducing the rest of the material in the "layers" section. However, that material labeled "reduced heat loss" is really orphan material, a legacy of earlier version of the article. It's material that might arguably be helpful to include in some way. But, it's NOT a good match to the other material in the section, being part of a fundamentally different narrative. Placing it in an introductory position confuses and undermines the subsequent material rather than supporting it.

I perceive the sections involved, which have been reverted to the headings "Simplified models" and "Why surface and outgoing emissions differ" as being immature and in need of further elaboration, organization, and improvement.

But, I don't see that particular attempt at improving matters as having been successful.

If it's important to make changes here, perhaps you could name what objectives you'd like such changes to attend to? Rhwentworth (talk) 02:44, 9 July 2023 (UTC)

I folded the section on "Reduced heat loss" up into the longwave radiation section, and day night as an add on into that area. As you said, the content was just orphaned where it was. It's also simple, introductory content, so it belongs higher up in the article.

"Why surface and outgoing emissions differ" is really the whole point of the article, so having an individual section titled that doesn't work. Section titles need to describe what, specifically, is going to be in the section. My reading of that section is that it is really focused on the lapse rate and effects at altitude, so for now I simply raised up the title of "Lapse rate". Efbrazil (talk) 00:56, 14 July 2023 (UTC)

There are two categories of narrative about the greenhouse effect: surface-energy-flow narratives and top-of-atmosphere (TOA) energy balance narratives. The surface energy budget narratives are so often problematic that one prominent climate textbook (Principles of Planetary Climate by Pierrehumbert) refers to undue focus on such narratives as the "surface budget fallacy." Such narratives aren't exactly wrong, but they lead to false reasoning and false conclusions remarkably often.

Because explanations that focus on what happens near the surface (without reference to TOA) are so widespread, we likely need to include them in the article. However, I'd really like to keep the two types of narratives (TOA-focused and surface/lower-atmosphere-focused) separated within the article.

The "reduced heat loss" text is part of the "surface energy budget" narrative, while OLR is a key part of the "TOA energy balance" narrative. Putting them in the same section, as you've done, muddles together those two narratives in a way that I think reduces the clarity of both narratives.

The "reduced heart loss" text may be "simple" content, but it's also primarily associated with the problematic "surface budget" narrative. So, I don't agree that it "belongs higher up in the article."

- - -

You wrote "Why surface and outgoing emissions differ" is really the whole point of the article, so having an individual section titled that doesn't work.

But, that's not "the whole point of the article." Some of the article is about that. Other things the article is about include:

• "Why does it matter than surface and outgoing emissions differ?"
• The surface energy budget narrative (which doesn't relate to surface vs outgoing emissions)
• Random stuff: models, day-night cycle, greenhouse gases, climate change, other planets, etc.

Most of the material in the section you've labeled "Lapse rate" barely mentions the lapse rate, since that's only a fairly minor detail in what they're actually talking about. Rhwentworth (talk) 03:01, 15 July 2023 (UTC)

Prompting the section with an elementary school level question like "Why do surface and outgoing emissions differ?" is going to invite fifth graders to click in. A jargon filled, difficult to understand section needs a high level title that makes it clear to readers what they're in for. I'm open to other titles, but so long as the section remains full of jargon and difficult to digest, but it needs to relate to the content at the level of the content.

Two of the three sections in that area had "lapse rate" in the title, and all the sections are built on the idea as far as I can tell. That's why you begin the section by defining lapse rate and end with explaining how greenhouse gases and the lapse rate interact. I don't know how you can say that most of the section barely mentions lapse rate.Efbrazil (talk) 20:02, 15 July 2023 (UTC)

Greenhouse gases and LW vs SW absorption

There seems to be a difference of opinion on what to say about greenhouse gases and the absorption of longwave/shortwave radiation. So, let's talk things through here, if there is a remaining disagreement.

My prior version of the text was:

A gas is a greenhouse gas if it absorbs longwave radiation. Greenhouse gases absorb longwave radiation more strongly than they do shortwave radiation.

@Efbrazil asserted "The last sentence is in conflict with sources, which say that the only measure of a greenhouse gas is whether it absorbs longwave radiation or not. I changed the second sentence to be factually correct." and altered the text to:

A gas is a greenhouse gas if it absorbs longwave radiation. Greenhouse gases that absorb more longwave radiation than shortwave radiation cause the greenhouse effect.

However, that change has actually changed things away from being factually correct, and away from alignment with what is said in the cited source. The cited source Wallace (2006) says (p. 121):

water vapor, carbon dioxide, and other gases whose molecules have electric dipole moments absorb radiation more strongly in the longwave part of the spectrum occupied by outgoing terrestrial radiation than the shortwave part occupied by incoming solar radiation.

The phrase "water vapor, carbon dioxide, and other gases whose molecules have electric dipole moments" is describing greenhouse gases, justifying the sentence "Greenhouse gases absorb longwave radiation more strongly than they do shortwave radiation."

However, the edit by u/Efbrazil creates the implication that it is the difference between longwave absorption and shortwave absorption is what creates the greenhouse effect, and that if a gas aborbed both equally, such a gas would not contribute to the greenhouse effect. That implication is factually incorrect (see below*), and is not supported by the source. So, I reverted that change.

There was, however, an additional concern in the change comment, the part saying "the only measure of a greenhouse gas is whether it absorbs longwave radiation or not." My reading of the original text is that it wasn't saying absorbing more longwave than shortwave is a "measure of a greenhouse gas", only that it happens to be true in practice that greenhouse gases absorb longwave more strongly than shortwave. So, I think the original text was correct. But, I concede that it could be misread as suggesting that this is a fundamental characteristic that is a "measure" of whether something is a greenhouse gas. So, my edit also added a prefix "In practice" to try to clarify this. I've reverted/modified the text to be:

A gas is a greenhouse gas if it absorbs longwave radiation. In practice, greenhouse gases absorb longwave radiation more strongly than they do shortwave radiation.

So, that's the current text, which we can discuss if there is a remaining disagreement.

- - -

*The formal definition of the greenhouse effect (longwave surface radiation not reaching space) considers only longwave effects. The definition doesn't care about shortwave absorption properties. A gas could absorb more shortwave than longwave and still contribute to the greenhouse effect.

Of course, given that only longwave radiation matters to the formal definition, one might question the entire final paragraph of the lead-in, which is about longwave vs. shortwave. I pondered for a while whether it makes sense to include such a paragraph. On balance, I think retaining it makes sense. My own analysis tells me that there could be a greenhouse effect even if there was more shortwave absorption than longwave absorption, but not if things get to the point where the atmosphere is 100% opaque to shortwave radiation. So, although the greenhouse effect is formally defined in a way that relates to only longwave radiation, that definition seems to exist within a context where it is understood that there is at least some degree of transparency to shortwave radiation. My read of additional text in Wallace 2006 supports this understanding. So, I think it's reasonable to talk about the atmosphere being largely transparent to shortwave radiation while absorbing longwave, as an aspect of the greenhouse effect, even if it's not part of the formal definition. Rhwentworth (talk) 22:45, 18 July 2023 (UTC)

Technical subtleties aside, all that I'm really interested in for this part of the lead is to express in some way the differential absorption of short vs long wavelengths. As long as that concept is not glossed over, I'll almost certainly be OK with almost any way of expressing it as long as it's concise. —RCraig09 (talk) 02:19, 19 July 2023 (UTC)

That sentence is the conclusion to the entire lead, so it needs to be clear and concise. I'm not sure what "in practice" means or whether the sources back it up. It seems to be more something that Rhwentworth thinks is right. My preference would be to simply cut the last sentence at this point since we can't say anything clear about the issue of differential absorption of short vs long wavelengths. Efbrazil (talk) 04:12, 19 July 2023 (UTC)

The phrase "in practice" is intended to convey that, while greenhouse gases absorb LW radiation more strongly than SW radiation, even though this is not a fact that defines whether something is considered to be a greenhouse gas. It was meant as a solution to your assuming it was meant to be a defining characteristic even though that had not been said. I take it the phrase doesn't help, in that regard, for you.

As to "whether the sources back it up", above I had quoted the exact text from a source that backs that up. What do you find unclear about that quote? (Again, Wallace 2006 says "water vapor, carbon dioxide, and other gases whose molecules have electric dipole moments absorb radiation more strongly in the longwave part of the spectrum occupied by outgoing terrestrial radiation than the shortwave part occupied by incoming solar radiation.")

I'm puzzled as to why you are so unclear about this.

At the same time, I'm not at all attached to including this particular point. I just want the point to be expressed correctly, if it is expressed at all.

I'd also like the whole paragraph in which the statement appears to make sense. If we dropped that last sentence, I'd want to add something so the paragraph doesn't seem incoherent or pointless. One option would be to replace the current last two sentences with something like:

Earth's atmosphere transmits a majority of shortwave radiation (absorbing 23% of sunlight), and absorbs a majority of longwave radiation (absorbing 90% of thermal radiation emitted by the surface).[citation: NASA 2010 Earth's Energy Budget chart]

That might be more interesting and relevant than what we're currently saying in that paragraph about greenhouse gases. Thoughts? Rhwentworth (talk) 11:41, 19 July 2023 (UTC)

The differential-absorption concept is very important to include, because it is what explains the general description in the first paragraph: "stars emit shortwave radiation that passes through greenhouse gases, but planets emit longwave radiation that is partly absorbed by greenhouse gases". As Rhwentworth remarks, keeping the last sentence, in some form, lets the final paragraph make sense in context. —RCraig09 (talk) 16:00, 19 July 2023 (UTC)

I much prefer RHwentworth's 2010 energy budget synposis. It is precise and sourced and has actual data. I changed the lead text to a tightened up version of that text. Hopefully happy for all? Efbrazil (talk) 20:26, 21 July 2023 (UTC)

I'm totally impressed by the pleasant way you've introduced numbers that are understandable to laymen in the context of the final paragraph. I just added a phrase that "closes the loop" and explains how GHE causes GW, a goal that I think is important. I'm not tied to that exact wording, of course. —RCraig09 (talk) 20:35, 21 July 2023 (UTC)

I amended the phrase "aborbs 90% of outgoing longwave radiation" to "absorbs 90% of the longwave radiation emitted by the surface" since the phrase "outgoing longwave radiation" conventionally mean radiation that reaches space, rendering the prior phrasing at best unclear and at worst incorrect; the revised text is rigorously correct, and I think clearer.

As to the text that "closes the loop", i.e., "thus accumulating energy and warming the Earth's surface"... I'm ambivalent about that clause, which I don't know how to translate to any rigorous underlying math that I know to be true:

• Neither the %SW absorbed nor the %surface-LW absorbed are numbers of central importance in the math associated with "accumulating energy." It's not that they don't matter at all, but exactly how much they matter is a bit unclear.
• The idea of "energy accumulating" is real only relevant to non-steady-state conditions when the greenhouse effect is increasing. If we're just talking about the baseline steady-state greenhouse effect, then asserting that energy is "accumulating" seems a bit confusing.

I understand the desire to link this paragraph back to the phenomenon of the greenhouse effect making things warmer. I'm a bit uneasy about the text @RCraig09 offered to address that purpose. And... I don't currently have something better to offer, which would both be more correct and meet the goals for simplicity. Rhwentworth (talk) 00:16, 22 July 2023 (UTC)

I think that currently increasing GHG concentrations imply that the GHE is increasing, so that energy is, in fact, accumulating. When GHG concentrations finally stabilize in a few decades, we can change the text. ;-) —RCraig09 (talk) 03:58, 22 July 2023 (UTC)

Reducing overlap with greenhouse gas

I've been doing a bit of work on the greenhouse gas article lately (even though I have no technical expertise in this field, please excuse me if I get anything wrong). I am trying to reduce excessive overlap between that article and the greenhouse effect article (it's even occurred to me if merging the two articles could be worth debating). At this stage, I would be inclined to move some of the content that is currently in the section called "greenhouse gases" to greenhouse gas; maybe also utilising excerpts. Anyone has any objections or anyone can help with this effort? Please also see on the talk page of the other article: https://en.wikipedia.org/wiki/Talk:Greenhouse_gas#Potential_for_trimming? EMsmile (talk) 19:57, 4 August 2023 (UTC)

With-and-without GHE diagram

@Efbrazil, @RCraig09: I've created a new with-and-without GHE figure. Draft is available HERE (Version 1). Thoughts?

This version might include too much information. All that is needed is the upward thermal radiation. Including downward thermal radiation and net radiative heat flow are unnecessary distractions that probably confuse matters.

ADDED: Ok, I've created a SIMPLER VERSION (Version 2).

For comparison, this was a prior proposed figure] that shares some of the same ideas, but without actual plots. --Rhwentworth (talk) 02:06, 8 June 2023 (UTC)

Though both Versions 1 and 2 still haves jargon, Version 2 is most readily understood—if a caption provides an explanation of what "thermal radiation" is and how it differs from what Everyman understands. If you want to achieve an exhaustively technically accurate presentation, this entire process must be a progressive education of the reader from the simple to the complex. It's expected that you'll lose progressively larger portions of the readership as you proceed. Much of what you're doing is at such a level of technical detail that it will never matter to the lay reader of a high level article. Version 2 with a helpful caption is a good "early chapter" of the explanation. —RCraig09 (talk) 06:04, 8 June 2023 (UTC)

Sourcing of each diagram is another consideration. —RCraig09 (talk) 06:12, 8 June 2023 (UTC)

One source is this page from the University of Chicago. With appropriate parameter settings, it yields both the "with GHE" and "without GHE" curves. (To get the "without GHE" curve, one must adjust the surface temperature until there is no overall energy imbalance.) Rhwentworth (talk) 20:48, 8 June 2023 (UTC)

I like version 2, although I'm not sure it is correct because it looks like you are comparing the planet without any atmosphere to one where there is an atmosphere. Even without greenhouse gases, wouldn't the atmosphere still provide a slight insulating effect due to stuff like convection and conduction with the surface? I understand it's tricky as the planet would freeze over and block latent heat transfer. I guess that's partly why people are so confused by Snowball Earth- between albedo and latent heat transfer how did the planet ever escape that state?

Also, I would cut the word flux and I think it's just as good, with the top label just saying "Thermal radiation" and the bottom saying "Temperature".

I also think labeling the white part of the diagram as the "greenhouse effect" is confusing. It seems like it should be the curved colored part, since that is where the extra heat is. Efbrazil (talk) 17:48, 8 June 2023 (UTC)

The "no GHE" diagram does include an atmosphere, albeit one without GHGs or clouds. In the absence of these, no, the atmosphere does NOT provide any insulating effect. This is because it is only GHGs and clouds that prevent every bit of the thermal radiation emitted by the surface from reaching space. Convection and conduction in the atmosphere would be irrelevant to that fact.

It the absence of GHGs and clouds, convection and conduction don't affect planetary radiative equilibrium no matter what they do. But, if you're curious about what happens to convection in the no-GHE case, it's as follows:

• Convection and atmospheric circulation would be very weak. In the with-GHE atmosphere, what drives convection and atmospheric circulation is the temperature difference between the "heat source" at the surface (where sunlight is being absorbed) and the "heat sink" at a high altitude where GHGs are emitting thermal radiation to space. In the no-GHE case, that heat sink is absent. The only heat sink is the cooler surface in the polar regions. The temperature difference between the tropics and the poles would be much less effective at driving atmospheric circulation (compared to the temperature difference between low and high altitudes in the with-GHE case).
• All that the weak convection and conduction would do is transport heat from the tropics toward the polar regions. They would move heat laterally over the surface of the globe, but would play no role in moving heat to space (which is a role that they serve in an atmosphere with GHGs).

As for how Earth escaped a snowball state, I think the leading hypothesis is that a series of massive volcanic events introduced enough CO2 to initiate a non-frozen climate.

One thing that people have trouble thinking about is that illustrations like sub-chart (b) reflect a scenario in which the greenhouse effect is gone, but other things (i.e., planetary albedo) are unchanged. People seem to have trouble dealing with that sort of abstract hypothetical. They get hung up on thinking about things changing practice, if one could really get rid of GHGs, and get confused.

Thats why I often prefer to simply compare the surface temperature to the planetary "effective temperature"; that involves no hypotheticals (and is what scientists calculate in practice). Though, it does require understanding the significance of the planetary effective temperature (the temperature needed to emit enough thermal radiation to balance sunlight), so there is no easy way of making things clear to everyone.

As an alternative, it can also be useful to look at an instantaneous no-GHE scenario: What would happen if the Earth was in its current state, and one magically turned off the ability of CO2, water vapor, and clouds to absorb thermal radiation? Then, you would suddenly have a diagram like chart (b) but with an upward flux of 398 W/m². This would instantly create an energy imbalance, with planetary cooling exceeding planetary warming by a massive 158 W/m² (i.e., the size of the greenhouse effect). This massive imbalance would rapidly lower temperatures. The end state wouldn't be the classic -18℃ because Earth's albedo would change. However, it's clear that things would get much colder. This way of talking about things has the advantage that it involves an instantaneous hypothetical, not a hypothetical equilibrium state in which one is temped to think about all the different factors which would be different.

It's tricky to explain greenhouse effect warming in a way that people "get it." Rhwentworth (talk) 21:39, 8 June 2023 (UTC)

The amount of volcanic activity required to break the snowball earth state is hard to imagine. It's off topic but interesting to consider, as it's one of those big mysteries in science that really hasn't been figured out.

I read up some more and I think you are right about all the insulating effect of the atmosphere coming from greenhouse gases. Amusingly, chatgpt disagreed, but I was able to convince it otherwise. I think it's possibly an interesting point to get across- that the earth without greenhouse gases would be the same temperature as the earth without any atmosphere at all.

I maintain that your graphics will be much more intuitive if you point to the extra heat near the surface as being the greenhouse effect, instead of describing the dead space above the extra heat as the greenhouse effect. Maybe I'll take a crack at that if you don't. Efbrazil (talk) 18:20, 9 June 2023 (UTC)

Comparison of Earth's upward flow of infrared thermal radiation in reality and in a hypothetical scenario in which greenhouse gases and clouds are removed or lose their ability to absorb thermal radiation—without changing Earth's albedo (i.e., reflection/absorption of sunlight). Top shows the balance between Earth's heating and cooling as measured at the top of the atmosphere (TOA). Panel (a) shows the real situation with an active greenhouse effect. Panel (b) shows the situation immediately after absorption stops; all thermal radiation emitted by the surface would reach space; there would be more cooling (via thermal radiation emitted to space) than warming (from sunlight). This imbalance would lead to a rapid temperature drop. Panel (c) shows the final stable steady-state result, after the surface cools sufficiently to emit only enough thermal radiation to match the energy flow from absorbed sunlight. The amount of thermal radiation emitted by the surface depends on its temperature.

I've integrated the discussion thus far and produced a figure File:Outgoing radiation with and without Greenhouse effect.svg I've tried to make it clearer that the greenhouse effect is neither the white space nor the blue, but simply the difference between what is emitted and what reaches space. I've also simplified the language in the X-axis labels.

You're definitely accumulating quite portfolio of thoughtful graphics! I don't mean to add to your workload, but to represent evolving physical scenarios, one could use [[GIF]s (GIMP is free), though some in this community dislike GIFs for being distracting. —RCraig09 (talk) 03:25, 9 June 2023 (UTC)

@RCraig09: Regarding GIFs... Thanks for the suggestion. However, I am among those who find GIFs to be too distracting to want to include them directly in an article. I wish there was a way to cause them to animate only when requested, but I don't see such a capability being available. Rhwentworth (talk) 20:06, 11 June 2023 (UTC)

We have 3 surface temperatures in these graphs- the 15 C of the Earth now, the -20C of the earth without an atmosphere, and then a set point of about -100C for what the earth would be without sunlight at all. However, the Earth would be the temperature of outer space in that case, right? More like -400C, not -100C. What am I missing? Efbrazil (talk) 19:41, 10 June 2023 (UTC)

What you are missing is that the bottom scale is very non-linear. So, you're misinterpreting if you think the graph indicates a set point of about -100℃ without sunlight. It doesn't.

The temperature of outer space is 3K or -270℃. I have added that to the scale in the figure.

Does that help?

I appreciate you pointing this out so that the point could be clarified in the diagram.

(Note that -18℃ doesn't require no atmosphere; it simply requires no greenhouse gases or clouds, i.e., no absorption of thermal radiation in the atmosphere.) --Rhwentworth (talk) 20:40, 10 June 2023 (UTC)

Thanks, that makes more sense, although it raises another point of confusion for me. You are saying that the greenhouse effect as a measurable quantity is suppressing 40% of thermal radiation escaping to space, but that the temperature effect is only a matter of going from -18C to 15C, which is obviously a lot less than a 40% increase given a baseline of close to -270C. Put another way, if the temperature impact was a 40% increase on top of going from -270C to -18C, then Earth's surface temperature would be about 89C. Can you explain to me the discrepancy? Is there a way to relate the two numbers? Efbrazil (talk) 02:06, 11 June 2023 (UTC)

Plot shows the temperature needed to emit a given amount of thermal radiation

If one expects the relationships to be linear, then nothing will make sense. The actual relationships are fairly simple, if highly non-linear.

The power emitted at the surface is $\mathrm {SLR} =\sigma T^{4}$, so the radiation flux changes about 4 times as fast as temperature does.

The formula for the surface effective temperature, $T$, relative to the power outgoing to space, is

$T=\left[{\frac {\mathrm {OLR} }{(1-{\tilde {g}})\,\sigma }}\right]^{1/4}$

where OLR is outgoing longwave radiation, σ is the Stefan-Boltzmann constant, and ${\tilde {g}}$ is the normalized greenhouse effect.

For ${\tilde {g}}=0.40$, $(1-{\tilde {g}})^{1/4}=0.88$, and $1/(1-{\tilde {g}})^{1/4}=1.14$.

So, a 40% suppression of radiation raises the surface temperature by 14%.

Temperature needs to be given in Kelvin, for all this to work. The Kelvin temperature is 273.15 + temperature in Celsius.

Does that help? Rhwentworth (talk) 06:55, 11 June 2023 (UTC)

Thanks, that's a fantastic explanation! I see the information in the section on "as a measurable quantity" too. The graph is very helpful for seeing the relationship. Efbrazil (talk) 19:40, 11 June 2023 (UTC)

I've put the temperature vs. radiation plot into the "as a measurable quantity" section too, to help others see the relationship as well. Rhwentworth (talk) 20:37, 11 June 2023 (UTC)

I created an image that is viewable on smartphone / thumbnail and tries to get the idea across more clearly. Let me know what you think. I could upload to wikimedia and put in the article if you like, or you could take some of the graphical ideas in here:

https://drive.google.com/file/d/10OfqUiHVl3znSWMja558PoYAHOPuN8bQ/view?usp=sharing Efbrazil (talk) 20:06, 11 June 2023 (UTC)

User:Efbrazil I like the directness and simplicity of your 20:06 drawing (especially the circular arrows that resemble those in the GHE drawing that was prominent for so long, and which capture the circular ~interception of energy). I'll leave it to others to verify the numbers on the horizontal axis, and I'm not sure what "heat without atmosphere" conveys; should it be "temperature without atmosphere"? But regardless, this diagram will help new readers to understand, assuming a concise caption is drafted. (Maybe Fahrenheit could be added, for the English-language encyclopedia.) —RCraig09 (talk) 21:02, 11 June 2023 (UTC)

Intriguing. I generally like the figure. And... I'd like to spend some time mulling over the nuances.

Some details that stimulate unease in me:

1. Labeling the range -270 to -18℃ as "Heat from sunlight" plays into a common source of confusion. It suggests that sunlight contributes that much energy, and the rest of the energy somehow magically is supplied by greenhouse gases. In truth, ever bit of the energy involved comes from sunlight. So, I find this particular label deeply problematic. That temperature range is actually something more like "Temperature without 'blanket' effect of greenhouse gases". But, that's probably too long to meet your needs.
2. You've labeled the upward radiation that is cancelled by downward radiation as "Thermal radiation intercepted by greenhouse gases." I'm still mulling over whether I think that's an accurate and fitting label. It might be. Still pondering.
3. You've drawn the radiative interface between space and the atmosphere as being at 20 km. In practice, that's a decent approximation, and is sometimes used. However, serious work often considers a higher boundary, such as 70 km. That's why my diagram just talked about energy balance at "top-of-atmosphere" without specifying exactly where that was. I have a slight nervousness that a climate skeptic might object that the whole atmosphere is not being considered, based on a drawing that shows the boundary at 20 km. I'm not sure if this is an issue that matters or not.

At the moment, #1 is my most serious concern.

I'll ponder including some of these ideas in my version of the diagram. Rhwentworth (talk) 21:02, 11 June 2023 (UTC)

Much concern could be avoided if the numerical altitude scale and the numerical "Energy flow" scale simply omitted the numbers. Readers here don't care about exact numbers (especially Watts/m^2). Probably the numeric temperature scale should remain, as temprature is directly meaningful to humans (Fahrenheit to Yanks ;-) ). —RCraig09 (talk) 21:13, 11 June 2023 (UTC)

Perhaps numbers for altitude could be omitted.

But, I like including numbers for energy flow, for a number of reasons:

1. Articles about the greenhouse effect and radiative forcing are constantly referring to energy flow numbers, so it's good for people to get a sense about the size of these numbers.
2. People often mistakenly treat temperature and "heat" as interchangeable in ways that are deeply confused, and which lead to false conclusions. I like to keep it clear how these two things are distinct. Including numbers supports that.
3. Without a scale for energy flow, it's not apparent how intensely nonlinear the relationship is between temperature and energy flow. Failure to appreciate that often leads to false reasoning.

Rhwentworth (talk) 21:23, 11 June 2023 (UTC)

@Efbrazil: If you include Farenheit, that creates a minor headache with regarding how to label the left-most temperature.

Is that label meant to be the temperature to emit no radiation, i.e., absolute zero, 0 K / -273℃ / -460℉, or is it meant to be the temperature without sunlight, i.e., the temperature of space, 3 K / 270℃ / -454℉? When we're dealing with Celsius, one can sort of finesse this issue, and say that we're just going to offer 2-significant digits for temperature, in which case the result is the same, either way.

(Technically, the top panel of "Warming" includes "Warming from the 3K microwave background radiation" -- but that amount is completely negligible compared to the intensity of sunlight. Including that would resolve any apparent contractions, but at the expense of introducing a confusing complication. It would hurt more than it helps, for most people.) Rhwentworth (talk) 21:36, 11 June 2023 (UTC)

Microdetail: since the center curved-triangle involves heat capture (warming), it could be reddish, to distinguish from blue cooling on the left side of the diagram. —RCraig09 (talk) 21:19, 11 June 2023 (UTC)

To be rigorous and pedantic: the curved triangle represents radiation being intercepted, not "heat." That radiation interception prevents the radiation from being "heat flow" (or net energy transfer).

But, it's generally true that the phenomenon in that region contributes to warming. Rhwentworth (talk) 21:26, 11 June 2023 (UTC)

I agree with @RCraig09 that "Heat without atmosphere" is confusing. We're not really drawing "heat", except in certain portions of the diagram. I'd prefer "Temp. w/out greenhouse gases".

There is a common false belief among some climate skeptics that the atmosphere causes warming but that warming has nothing to do with greenhouse gases. (They think it's simply atmospheric "pressure", though that's based on muddled thinking about the physics.) So, I prefer to focus on the comparison of with-and-without greenhouse gases, rather than with-and-without atmosphere. Rhwentworth (talk) 21:15, 11 June 2023 (UTC)

@Efbrazil: The latest version of File:Outgoing radiation with and without Greenhouse effect.svg incorporates a few styling points from your diagram. In particular, there are now up and down arrows in the energy balance section, and I've eliminated the redundant "cooling" bar. Rhwentworth (talk) 00:38, 12 June 2023 (UTC)

Thanks for the encouragement! I also modified my graphic as per what was said above:

Labels: I updated the labels at the bottom describing temperatures to work in isolation and to include what I think is all the critiques above. I still would like to somehow say that "no greenhouse gases" produces the same result as "no atmosphere", but that's probably not the place to say that.

Triangle color: The triangle is still showing thermal radiation, it is just showing it moving in a different direction, so I kept the colors the same. However, I think it's fair to say the color shouldn't be blue all the way, since that implies cooling purely. I went to a red to blue gradient, to clue people into the temperature at altitude.

Altitude labels: I left them as I don't want to get too hand wavy with the graphic. If people think it's really not correct to make the cutoff at 20 km then I'm not sure what to do, as I'd need to squish the triangle to fit, and then the triangle label wouldn't fit...

Updated graphic at same place, here:

https://drive.google.com/file/d/10OfqUiHVl3znSWMja558PoYAHOPuN8bQ/view Efbrazil (talk) 00:53, 12 June 2023 (UTC)

Thanks for the update. It's seeming promising.

• The color shading you've chosen does convey that it's warmer near the surface than it is higher up. But, there's a certain loss in not differentiating the coloring of the regions. You say "it's fair to say the color shouldn't be blue all the way, since that implies cooling purely"... well, if you were coloring the net-energy/heat-flow portion to the left, that is, in fact, purely cooling. You write that the triangle is "still showing thermal radiation, it is just showing it moving in a different direction"... that's one way of thinking about it; but I think it's more accurate to say that that region represents the portion of upward radiation that is being counterbalanced or canceled by downward radiation, so that there is an absence of a cooling effect. That's why I chose to make that area a lighter blue in my diagram. One could use a warm color if you equate an absence of cooling to warming. But, perhaps the lighter blue would more closely match what the region represents? I'm not sure if I'd prefer separate colors for the regions over you use of color to represent air temperature -- but I'd kind of like to see it both ways. ADDED: You could convey both if you do a gradient in both places, but increase transparency in the triangle, so it's a lighter version of the gradient?
• If you're unable to do superscripts in your tool, you could use a unicode superscript character to indicate square meters: ² I wouldn't want to see ^2 in the final version.
• A technical detail is that without the Sun, geothermal energy (about 0.08 W/m²) would raise Earth's surface temperature to very roughly 34 K / -239℃. So, the current label isn't entirely correct, technically. It's really "≈ -239℃ if only geothermal energy". Maybe one could use -240℃ to imply only 2-significant digits are being used. Not sure how that should be handled... Though it's a complication, it could be useful to acknowledge geothermal this way, since a common climate denial trope is that geothermal energy is responsible for climate change--when it's really way too small for that.
• If you upload it, please use a more specific title than "Thermal flow". That's too generic a term to claim with a specialized figure.

Rhwentworth (talk) 01:59, 12 June 2023 (UTC)

Thanks!

• I changed the colors to be light blue for the cooling area and gray to indicate neutrality for the greenhouse effect area, since in that area there is no directional flow. I also made it clear that the up arrows are flowing from not just the surface, but also from the thermal radiation intercepted by the greenhouse gases. Both changes I'm not wedded to, if you prefer the gradient or having the up arrows only at the top then let me know.
• Superscript fixed
• I changed the bottom axis labels again, this time to just explain the two temperatures that matter: -18C and 15C. One reason is to make it clear that the axis is not describing what's in the chart, since I don't want people thinking that the right side of the chart is higher temperatures. Secondly, I don't think we need to focus on the temperature of the Earth without a sun, that opens up a can of worms, like geothermal energy and steady state, and of course the Earth wouldn't have formed without the sun, so how far back are we going in establishing steady state?
• Title will change when uploading

Take a look and see if concerns are addressed. Same location:

https://drive.google.com/file/d/10OfqUiHVl3znSWMja558PoYAHOPuN8bQ/view Efbrazil (talk) 18:57, 12 June 2023 (UTC)

Thumbs up on the 18:57 version! (except, maybe removing absolute altitude numerals that aren't useful to the layman and aren't accurate enough for the scientific purist) —RCraig09 (talk) 19:11, 12 June 2023 (UTC)

It's continuing to improve.

• The visual style is a bit flat and dull-seeming; that's not fatal, but... The use of gradient might help with that? I'm thinking returning to the idea of a gradient from warm to cool, but making the gradient different in the two regions to differentiate them. I had envisioned using the the same gradient in both sections, then overlaying the triangle with a partially transparent white layer to mute the gradient there. I wanted to demonstrate that, but am not yet competent at GIMP, so I produced https://climatepuzzles.org/wp-content/uploads/2023/06/GHEThermalFlow-alt1.png instead, which perhaps has its own interesting qualities. (That version arose from overlaying a partially transparent gradient over the existing colors.) Probably, what I wanted to do would better differentiate the two regions? Ultimately, this point is about aesthetics without detracting from clarity--I'm not sure how to optimize it.
• The one thing I would consider changing about the labels is that I might consider changing the one label to "Cooling: Net thermal radiation to space". The reason it might be helpful to add "Net" is that that's what differentiates the two regions of the figure. The region to the left is "net" upward radiative thermal energy flow, and the region to the right is the upward thermal radiation flow that is cancelled out by an equal downward flow. Adding the word "net" offers a clue to what the diagram actually means, without, I hope, unduly complicating matters.
• Otherwise, labeling now seems pretty good.
• I'm okay with the choice to retain altitude numbers.

Rhwentworth (talk) 21:37, 12 June 2023 (UTC)

Gradients! I say Gradients! Gradients for the win! —RCraig09 (talk) 00:06, 13 June 2023 (UTC)

The addition of two separate gradients adds confusion for me, as I want to know what the gradients mean. If the gradient means temperature of the atmosphere at altitude then the colors between the two areas should be the same. If the color means directional flow of energy then there should only be 2 colors- light blue vs gray- as it is now.

I think the light blue and gray make the most sense since that's the central point of the diagram. The simplicity doesn't bother me, since this is primarily for smartphone and thumbnail. This is not meant to be a graphic you need to zoom into to understand.

I'm also not sure about adding "Net" to "thermal radiation to space". I personally find that more confusing than helpful. If we wanted to show up flow / down flow cancelling each other out on the right hand side then that's where we should do it- in the triangular area. I'll give it some thought... Efbrazil (talk) 00:20, 13 June 2023 (UTC)

The circular arrows already denote the two flows canceling each other out. I'm not sure if the background could try to indicate that without adding confusion. I thought of suggesting a warm color for the triangle, but upon thinking about the warming effect being indirect rather than direct, I'm actually liking the choice of a neutral gray for that area, with color reserved for the actual direct warming and cooling. Rhwentworth (talk) 04:04, 13 June 2023 (UTC)

Good! Graphic live on the page now, second in lead. I moved down the existing graphic to the "simplified models" area. I also changed "intercepted" to "trapped", which I think is perhaps more descriptive and common terminology. It also suggests an accumulation of infrared radiation, which I like. Efbrazil (talk) 16:37, 13 June 2023 (UTC)

I like the graphic and the placement.

However, I dislike the shift from "intercepted" to "trapped." To the extent that the idea of "trapping" is valid, it usually refers to thermal energy being trapped at the surface, unable to efficiently move upward towards space.

The idea of radiation being "trapped" seems dubious and likely to generate confusion and argument. Radiation isn't something that can be contained, except via mirrors (which are not present in the atmosphere). Instead, radiation is intercepted/blocked/absorbed/destroyed. Nor is radiation a conserved quantity which could somehow "accumulate." It's thermal energy that accumulates; radiation levels only increase as a side-effect of that energy accumulation.

Claiming that "radiation is trapped" also feeds into standard tropes of climate deniers, who routinely present explanations of how this couldn't possibly be true. That problem is bad enough when it's said that heat is trapped; implying that radiation is trapped is likely to aggravate matters.

So, I request a return to the use of "intercepted" in the diagram. The wording may be less familiar, but it's more accurate, and less prone to stimulating misunderstanding and resistance. Rhwentworth (talk) 20:55, 13 June 2023 (UTC)

I went with "absorbed" for now, as that arguably splits the difference between intercepted and trapped. The advantage of absorbed is that it makes it clear what the greenhouse gases are doing and why there is more heat in that area- the accumulation of energy. Intercepted just means two things connect with each other so it's kind of meaningless in forming a mental model. If you really don't like absorbed we can go back to intercepted. I also zoomed the graphic a tiny bit in the process (trimming back white space around it). Efbrazil (talk) 16:30, 14 June 2023 (UTC)

"Absorbed" is an interesting choice. Technically, the amount of radiation absorbed is in some ways more than what is in the grey triangle. I'm not sure off-hand how one would properly plot the amount "absorbed" on this type of diagram. But, the triangle likely shows what is absorbed without being replaced by an equivalent amount being emitted upward? So, the gray triangle is what is "effectively absorbed", I think? So, maybe "absorbed" is close enough to being true to live with, at the level of discourse offered by the diagram. I'll mull over a bit more. Okay for now.

(What the triangle really represents is upward radiation cancelled out or negated by greenhouse gases sending an equivalent amount of radiation downward, so that there is no contribution to net energy transfer. But, I can't think of a one-word way of encapsulating that which would be at all clear.)

Thanks. Rhwentworth (talk) 18:08, 14 June 2023 (UTC)

Ah, I see what you mean by absorbed not conforming to the energy quantity the graph is showing. I changed absorbed to redirected, I think that's more technically correct, particularly as it is coupled with the circling arrow thing. So it now says "Thermal radiation redirected by greenhouse gases". Good? Efbrazil (talk) 20:31, 14 June 2023 (UTC)

I think “redirected” works. Thanks. Rhwentworth (talk) 01:33, 15 June 2023 (UTC)

Just as a note: the 4th power only applies to a black or gray body.

Earth’s outgoing longwave radiation linear due to H2O greenhouse effect

https://doi.org/10.1073/pnas.1809868115 2003:E5:273D:D00:75D3:B893:3662:D13C (talk) 21:13, 19 August 2023 (UTC)

Idealized greenhouse model and Illustrative model of greenhouse effect on climate change?

I don't understand how these two articles related to this: Idealized greenhouse model and Illustrative model of greenhouse effect on climate change? Are they important sub-articles? Should they introduced better, not just under "see also"? EMsmile (talk) 16:56, 18 December 2023 (UTC)

Is the section on clouds any good?

I came here today because I was working on cloud feedback and thought I could transcribe a text block from the section on clouds in this article. I have some doubts though about the quality of content in the clouds section. My doubts stem from the fact that the content is unsourced and that it was added in one go by a student a year ago in this edit. Can someone who knows a bit about clouds please take a look? Also, one has to wonder what content should be at cloud feedback exactly, given that content is located e.g. at climate change feedback, climate sensitivity, greenhouse effect. For now, my idea was to mainly use excerpts. EMsmile (talk) 10:24, 25 September 2023 (UTC)

I have decided to remove the content in question due to my concerns that I voiced above on 25 Sept. (mainly: unsourced, unnecessary overlap/repetition with other articles). This is the content that I removed:

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Clouds include liquid clouds, mixed-phase clouds and ice clouds. Liquid clouds are low clouds and have negative radiative forcing. Mixed-phase clouds are clouds coexisted with both liquid water and solid ice at subfreezing temperatures and their radiative properties (optical depth or optical thickness) are substantially influenced by the liquid content. Ice clouds are high clouds and their radiative forcing depends on the ice crystal number concentration, cloud thickness and ice water content.

The radiative properties of liquid clouds depend strongly on cloud microphysical properties, such as cloud liquid water content and cloud drop size distribution. The liquid clouds with higher liquid water content and smaller water droplets will have a stronger negative radiative forcing. The cloud liquid contents are usually related to the surface and atmospheric circulations. Over the warm ocean, the atmosphere is usually rich with water vapor and thus the liquid clouds contain higher liquid water content. When the moist air flows converge in the clouds and generate strong updrafts, the water content can be much higher. Aerosols will influence the cloud drop size distribution. For example, in the polluted industrial regions with lots of aerosols, the water droplets in liquid clouds are often small.

The mixed phase clouds have negative radiative forcing. The radiative forcing of mix-phase clouds has a larger uncertainty than liquid clouds. One reason is that the microphysics are much more complicated because the coexistence of both liquid and solid water. For example, Wegener–Bergeron–Findeisen process can deplete large amounts of water droplets and enlarge small ice crystals to large ones in a short period of time. Hallett-Mossop process will shatter the liquid droplets in the collision with large ice crystals and freeze into a lot of small ice splinters. The cloud radiative properties can change dramatically during these processes because small ice crystals can reflect much more sun lights and generate larger negative radiative forcing, compared with large water droplets.

Cirrus clouds can either enhance or reduce the greenhouse effects, depending on the cloud thickness. Thin cirrus is usually considered to have positive radiative forcing and thick cirrus has negative radiative forcing. Ice water content and ice size distribution also determines cirrus radiative properties. The larger ice water content is, the more cooling effects cirrus have. When cloud ice water contents are the same, cirrus with more smaller ice crystals have larger cooling effects, compared with cirrus with fewer larger ice crystals. EMsmile (talk) 23:08, 18 December 2023 (UTC)

References

Section on aerosols

I've also removed the text block on aerosols that had been added by another student, for the same reason: it overlaps too much with other articles and the content was not up to date. Will use an excerpt instead:

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There are two major sources of atmospheric aerosols, natural sources, and anthropogenic sources. Natural sources of aerosols include desert dust, sea salt, volcanic ash, volatile organic compounds (VOC) from vegetation and smoke from forest fires. Aerosols generated from human activities include fossil fuel burning, deforestation fires, and burning of agricultural waste. The amount of anthropogenic aerosols has been dramatically increased since preindustrial times, which is considered as a major contribution to the global air pollution. Since these aerosols have different chemical compositions and physical properties, they can produce different radiative forcing effects, to warm or cool the global climate.

The impact of atmospheric aerosols on climate can be classified as direct or indirect with respect to radiative forcing of the climate system. Aerosols can directly scatter and absorb solar and infrared radiance in the atmosphere, hence it has a direct radiative forcing to the global climate system. Aerosols can also act as cloud condensation nuclei (CCN) to form clouds, resulting in changing the formation and precipitation efficiency of liquid water, ice and mixed phase clouds, thereby causing an indirect radiative forcing associated with these changes in cloud properties.

Aerosols that mainly scatter solar radiation can reflect solar radiation back to space, which will cool the global climate. All of the atmospheric aerosols have the capability to scatter incoming solar radiation, but only a few types of aerosols can absorb solar radiation. These include black carbon (BC), organic carbon (OC) and mineral dust, which can induce non-negligible warming effects. The emission of black carbon is significant in developing countries, such as China and India. Black carbon can be transported over long distances, and mixed with other aerosols along the way. Solar-absorption efficiency has a positive correlation with the ratio of black carbon to sulphate.

Particle size and mixing ratio can not only determine the absorption efficiency of BC, but also affect the lifetime of BC. The surface albedo of snow and ice can be reduced due to the deposition of absorbing aerosols, which will also cause heating effects. The heating effects of black carbon at high elevations can be as important as carbon dioxide in the melting of snowpacks and glaciers. In addition to these absorbing aerosols, it is found that the stratospheric aerosols can also induce local warming by increasing longwave radiation reaching the surface and reducing outgoing longwave radiation. EMsmile (talk) 23:42, 18 December 2023 (UTC)

References