
55Radiatively Important Atmospheric Constituents
some of it is reected, scattered, and absorbed by the atmosphere, but where
most of it reaches the earth’s surface. This energy absorbed by the planet
is then released from the surface as long wave (infrared) radiation, which
would otherwise be transmitted to space without the existence of the green-
house gases. Instead, this infrared radiation is intercepted, absorbed, and
retransmitted by the greenhouse gases, resulting in energy being trapped in
the earth–atmosphere system. Figure 2.7 summarizes the key radiative pro-
cesses of the greenhouse effect. Without this effect, the average temperature ...