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Effects of Clouds
Now if we consider the effect of clouds, we get a quite different
picture. Figure 4 (Harrison et al, 1988) shows outgoing
radiation, including effects of clouds, averaged over the entire month of
April 1985. Comparing this with the clear-sky photograph shown above, you
see that the tropical areas have a much lower outgoing longwave radiation.
In fact, some areas over Indonesia, South America, and Africa on the
Equator
have temperatures comparable with polar regions. How can this be? A
review of the temperature structure of the atmosphere and your observations
of cloud patterns from satellite photographs from the third unit will
help answer this question. Very strong surface heating in the tropical
regions gives strong convection that creates very deep cloud layers, the
tops of which are very high and therefore very cold.
PREVIOUS: Outgoing Radiation Under Clear-Sky Conditions
