Question by : How do green house gases absorb and then re-radiate heat back to the earths surface?
Ok I know that green house gases retain some of the outgoing infrared radiation, but my question is how? On a sub-atomic scale, how does everything interact?
Thanks
Best answer:
Answer by Paul B
This is actually quite a complicated question.
Greenhouse gases absorb energy from the outgoing infrared radiation. This happens fairly close to the ground. Then they re-radiate it to the gas higher up, and so on. At each stage, part of the radiation goes to heat the gas. The amount of radiation that each layer passes on depends on its temperature. The total amount of radiation eventually emitted depends on the temperature near the top of the atmosphere.
The more you have of a greenhouse gas, the higher up in the atmosphere the final emitting layer is. And since the higher you get, the colder, more greenhouse gas means a colder final emitting layer, and less energy lost to space.
This certainly makes the world much warmer than it otherwise would be, and informed scientific opinion is that with more than 90% certainty, anthropogenic greenhouse gases are contributing to increased warming at an unprecedented rate.
See
http://royalsociety.org/displaypagedoc.asp?id=20742
endorsed by the [US] National Academy of Sciences, Chinese Academy of Sciences, Indian National Science Academy, , Russian Academy of Sciences, Royal Society (London). Over 40 other academies of national stature have issued similar statements:
http://en.wikipedia.org/wiki/Scientific_opinion_on_climate_change#Academies_of_Science
(If links fail, cut, paste, and join up
http://royalsociety.org/
displaypagedoc.asp?id=20742
and
http://en.wikipedia.org/wiki/Scientific
_opinion_on_climate_change
#Academies_of_Science)
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