Richard 111's comment - Sunsettommy - 09-12-2012
September 8, 2012 at 5:09 pm · Reply · Edit
I’ve been looking up data on carbon dioxide. A TRACE gas (0.04%) in the atmosphere. What can a carbon dioxide molecule do? Not much. It can absorb or emitt radiation at 2.7, 4.3 and 15 um. (also 1.9 um slightly) Radiation at 2.7 and 4.3 microns is from the SUN ONLY!!! The carbon dioxide absorbs energy in those two bands preventing that energy reaching the surface.
But the 15 micron band is certainly available from the earth’s surface at all times, day and night. The question is; does carbon dioxide absorb any of this radiation? Umm… not really. The carbon dioxide gas in the atmosphere, up to the altitude of 9 kilometres, is already too warm to absorb much of that radiation. You see, peak radiation at 15 microns is -80C (yes minus!). Look up radiative heat transfer.
BUT, carbon dioxide is radiating at 15 microns because most of it is way ABOVE -80C. But this is NOT ‘back radiation’. It is perfectly natural.