Geoscience Reference
In-Depth Information
180°
150°
120°
90°
60°
30°W
0°
30°E
60°
90°
120°
150°
180°
60°
60°
32
30°N
30°N
24
1
2
0°
0°
30°S
30°S
4
8
60°
8
60°
8
60°
180°
150°
120°
90°
60°
30°W
0°
30°W
90°
120°
150°
180°
Figure 3.24
The mean annual temperature range (
C) at the earth's surface.
Source: Monin (1975). Courtesy World Meteorological Organization.
°
Percent of hemisphere surface
internal energy. These two are therefore usually
considered together and termed the total potential
energy (
PE
). For the whole atmosphere
potential energy
0
25
50
75
100
300
Incomi
Surplus
≈
10
24
J
200
10
10
J
In a later section (Chapter 6C), we shall see
how energy is transferred from one form to
another, but here we consider only heat energy. It
is apparent that the receipt of heat energy is very
unequal geographically and that this must lead to
great lateral transfers of energy across the surface
of the earth. In turn, these transfers give rise, at
least indirectly, to the observed patterns of global
weather and climate.
The amounts of energy received at different
latitudes vary substantially, the equator on the
average receiving 2.5 times as much annual solar
energy as the poles. Clearly, if this process were
not modified in some way the variations in
receipt would cause a massive accumulation of
heat within the tropics (associated with gradual
increases of temperature) and a corresponding
deficiency at the poles. Yet this does not happen,
kinetic energy
≈
Deficit
6
4
100
2
90°
60°
50°
40°
30°
Latitude (°N)
20°
10°
0°
Figure 3.25
A meridional illustration of the
balance between incoming solar radiation and
outgoing radiation from the earth and atmosphere*
in which the zones of permanent surplus and
deficit are maintained in equilibrium by a poleward
energy transfer.†
Sources: *Data from Houghton; after Newell (1964). †After
Gabites.
and the earth as a whole is roughly in a state of
thermal equilibrium. One explanation of this
equilibrium could be that for each region of the
world there is equalization between the amount of
