Which part of solar radiation (visible light vs. infrared radiation) plays main part in keeping Earth's surface warm?

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    $\begingroup$ The answer to your question is "both". I'm trying to find a good reference, but you cannot say one is more important than the other as the Sun's energy is close to evenly split between the very narrow visible band and the much, much broader infrared band. Unreliable sources indicate the split at the top of the atmosphere is roughly 10% UV, 40% visible, and 50% infrared. Much less than 1% of the solar radiation energy at the top of the atmosphere lies outside the UV / visible / infrared bands. $\endgroup$ – David Hammen Jan 2 at 12:04
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    $\begingroup$ @DavidHammen And the albedo is the same for VIS and NIR? $\endgroup$ – Leos Ondra Jan 2 at 12:07
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    $\begingroup$ No, it is not, and neither is the absorption. The Earth's stratosphere absorbs much of the ultraviolet, and the troposphere absorbs more infrared than visible. However, that warming of the Earth's atmosphere indirectly warms the surface of the Earth. $\endgroup$ – David Hammen Jan 2 at 12:38
  • $\begingroup$ For future reference it's preferred to ask for a moderator's help to migrate a question than to delete one copy and then post a second copy somewhere else. Even though it's invisible to many users deletion is not really deletion as much as it is a partial invisibility cloak. $\endgroup$ – uhoh Jan 5 at 5:56
  • $\begingroup$ A link to the first copy of your question is still visible, but for people below a certain reputation score if they click that it will be invisible, and your message linking to the new copy which is now in a deleted post would also be invisible i.stack.imgur.com/NslVP.jpg to many/most users. $\endgroup$ – uhoh Jan 5 at 5:57

Electromagnetic radiation converts based on frequency and exposure. Visible light and Infrared waves are the predominant energy sources that can penetrate the atmosphere. Higher energy wavelengths (UV and above) do interact but are often bounced by significant portions. Those radiations interact with atmospheric gases; emit infrared waves in the process.

  • $\begingroup$ Infrared is stated to be the biggest contributor to heat (50%), followed closely by visible light (40%), then ultraviolet (10%). $\endgroup$ – Jonathan Jan 8 at 14:47


I asked an AI your question, and got the following response. I then analyzed / researched / verified it in the following sections.

Short answer - Infrared radiation is what heats the Earth the most, followed closely by visible light, though all frequencies do somewhat heat the earth.

AI generated answer to the question "Which part of solar radiation (visible light vs. infrared radiation) plays main part in keeping Earth's surface warm?":

The AI correctly responded with high confidence "Infrared Radiation".

My own human analysis of the AI's response: This is produced by the Dragon AI in AI Dungeon, which is likely correct because infrared light has more of a heating effect than visible light. This is correct per the data I researched below as well:

Researched answer: https://ag.tennessee.edu/solar/Pages/What%20Is%20Solar%20Energy/Sunlight.aspx

Much of the energy from the Sun arrives on Earth in the form of infrared radiation. Sunlight in space at the top of Earth's atmosphere at a power of 1366 watts/m2 is composed (by total energy) of about 50% infrared light, 40% visible light, and 10% ultraviolet light[1]. At ground level, this decreases to about 1120-1000 watts/m2, and consists of 44% visible light, 3% ultraviolet (with the Sun at the zenith (directly overhead), but less at other angles), and the remainder infrared. Thus, sunlight's composition at ground level, per square meter, with the sun at the zenith, is about 527 watts of infrared radiation, 445 watts of visible light, and 32 watts of ultraviolet radiation. The balance between absorbed and emitted infrared radiation has a critical effect on the Earth's climate.

If anyone can come up with another reference to strengthen this (or if anything contradicts this), please comment. I was not able to find anything beyond this link online.

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    $\begingroup$ Unfortunately, the sole reference on the linked page is to a Wikipedia article that does not support the claim. $\endgroup$ – David Hammen Jan 2 at 20:11
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    $\begingroup$ -1: What is this? First part of the answer states "only IR" while the second part of the answer and comments above clearly show its "not only IR". How can the author of this answer not see this blatant discrepancy and comment on it at least? Also the 'human analysis' (your work?) essentially says "its IR because its IR", which is circular logic and therefore doesn't say anything. Please improve. $\endgroup$ – AtmosphericPrisonEscape Jan 6 at 16:06
  • $\begingroup$ @AtmosphericPrisonEscape The first part is what the AI said, the second part is my reasoning, and finally, the "proof" - the research that backs up the answer. Infrared is indeed the biggest contributor per the research stated. I personally find it impressive the AI was able to correctly answer the question, and kind of funny it bragged about it. To clarify, infrared is the biggest contributor to heat, which was the original question. This is closely followed by visible light, then ultraviolet light. $\endgroup$ – Jonathan Jan 8 at 14:45
  • $\begingroup$ @AtmosphericPrisonEscape - I think I see and have addressed the source of your confusion: the question the AI answered was "Which part of solar radiation (visible light vs. infrared radiation) plays main part in keeping Earth's surface warm?" It correctly answered Infrared. $\endgroup$ – Jonathan Jan 8 at 15:12

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