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I'm trying to understand the atmospheric greenhouse effect. If CO2 absorbs lots of IR radiation emitted from the Earth's surface, does it not also shield the same wavelength radiation that is coming from the sun? Would this shielding not have a 'cooling' effect. Does CO2 block incoming IR from the sun?

What is the ratio of energy absorbed by atmospheric CO2 from IR coming from the Earth vs directly from the Sun?

Andy
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    The whole point is that the incoming (non IR) wavelengths coming in are reradiated as IR. I'm voting to close this as a duplicate because that other question (though different) has your answer. – Jan Doggen Jul 02 '19 at 11:07
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    the infrared radiation from the sun is shortwave infrared and is not stopped by the atmosphere,the earth emits infrared radiation in longwave radiation and a lot of this gets absorbed and radiated back to the suface of earth(the atmosphere behave like a hi pass filter in infrared) – trond hansen Jul 02 '19 at 12:21
  • I find it unlikely that the sun provides no IR in the same wavelength as CO2 absorbs. I'm trying to understand the relative scale between Earth CO2 IR back radiation and Sun direct CO2 wavelength IR radiation. – Andy Jul 02 '19 at 13:06
  • @Andy you can take a look here http://agron-www.agron.iastate.edu/courses/Agron541/classes/541/lesson09a/9a.3.html to see the composition of sunlight. – trond hansen Jul 02 '19 at 14:16
  • this is the part reaching the ground,most of the UVA reaches the ground and some of the UVB reaches the ground but no UVC-UVX reaches the ground,and as you can see shortwave ir reaches the ground but little longwave ir are able to reach the ground. – trond hansen Jul 02 '19 at 14:37
  • As others have noted, there is very little long-wave IR energy coming from the sun. What little there is, however, does not cause a cooling effect. It gets absorbed by the CO2 in the atmosphere just as outgoing radiation would be, and is thus a heating effect. Once that energy is absorbed it reradiates both downward and upward. – Mark Jul 02 '19 at 16:32

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