Geoscience Reference
In-Depth Information
Figure 3.22
Planetary short- and long-wave radiation (W
m-2
). (A) Mean annual absorbed short-wave radiation for the period April
1979 to March 1987. (B) Mean annual net planetary long-wave radiation (
L
n
) on a horizontal surface at the top of the atmosphere.
Sources
: (A) Ardanuy
et al
. (1992) and Kyle
et al
. (1993)
From Bulletin of the American Meteorological Society
, by permission of the American
Meteorological Society. (B) Stephens
et al
. (1981).
cover about 62 per cent of the earth's surface on average.
A further nine units are similarly reflected from the
surface and three units are returned by atmospheric
scattering. The total reflected radiation is the
planetary
albedo
(31 per cent or 0.31). The remaining forty-nine
units reach the earth either directly (
Q
= 28) or as diffuse
radiation (
q
= 21) transmitted via clouds or by down-
ward scattering.
The pattern of outgoing terrestrial radiation is quite
different (see Figure 3.22). The black-body radiation,
