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Surface Temperature Regulation
If a planet has no water vapor in its atmosphere, then its surface
temperature is determined primarily by the abundance of carbon dioxide in
its atmosphere. Planet Venus has an atmosphere consisting of 98% carbon
dioxide and surface pressure 90 times that of Earth. Solar energy, which
is mostly visible radiation, passes through the window in the visible
range (carbon dioxide has no absorption between 0.4 and 0.7 microns) and
strikes the surface where, according to the table of albedos, 24% is
converted to heat. The large amount of carbon dioxide in the Venus
atmosphere produces a very strong greenhouse effect that re-radiates
infrared energy back to the surface giving a surface temperature of 477oC.
Planet Mars, on the other hand, has at atmosphere of 95% carbon dioxide but
a surface pressure less than 1/100 of that of Earth. This rather low total
mass of carbon dioxide can only create a very weak greenhouse effect on
Mars, and its surface temperature is -53oC. The temperature of a planet's
surface is more related to the amount of carbon dioxide in its atmosphere
than to its position relative to the sun.
The important concept from this discussion is that greenhouse gases in general, and carbon dioxide in particular, regulate the temperature at the planet surface. The fact that earth has far less carbon dioxide than Venus and considerably more than Mars gives earth a unique range of surface temperature that is favorable for plant, animal, and human life as we know it.
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