Geoscience Reference
In-Depth Information
LONGITUDE
150
120
90
60
30
0
30
60
90
120
150
180
80
80
12
12
50
60
25
75
50
100
125
25
25
50
40
40
50
100
12
75
50
100
25
50
150
75
25
25
150
175
150
12
12
25
125
10
100
20
50
20
50
150
75
12
125
25
50
125
100
75
125
75
0
75
0
100
75
50
100
50
150
50
150
125
25
20
125
25
75
20
10
125
25
125
100
50
50
12
50
100
100
125
25
75
75
40
40
75
12
50
50
50
60
60
90
60
30
0
30
60
90
150
120
120
150
180
Source: After Budyko et al. (1962)
atmosphere. More specifically it is the temperature of the
air (
T
) multiplied by the specific heat (
Cp
)
1
of the air at
a constant pressure. Sensible heat is gained from the
ground surface after the absorption of short-wave radia-
tion, or by the release of latent heat through condensation.
The potential energy of the atmosphere is essentially a
function of its height above the ground surface (
z
); gravity
(
g
) is a constant. As air moves in the atmosphere it tends
to change its height and alter its energy content. If the air
sinks slowly, the potential energy decreases. Normally it
is converted to sensible heat, and the air becomes warmer
as it subsides. If the air rises, the temperature tends to
decline but the potential energy increases.
Kinetic energy is proportional to the square of the
velocity of the wind (
V
2
/2). Therefore strong winds have
more kinetic energy than gentle winds, as the damage they
cause indicates. In fact, on a global scale, hurricanes and
other strong winds at the surface are relatively rare, so the
quantity of energy in the form of kinetic energy is limited.
Even in the regions of strongest winds it probably reaches
no more than 0ยท5 per cent of the total energy content of
the atmosphere.
The actual flows of energy can be shown more simply
if we consider them as part of a large system in which
we distinguish the inputs and outputs with feedback
between the different subsystems (
Figure 3.12
for radiant
Space
SHORT-
WAVE
INPUT
LONG-
WAVE
OUTPUT
Short-wave
to
atmosphere
Emission
of long
-wave
radiation
Reflection of
short-wave
radiation and
loss of
long-wave
radiation
Short-wave
to
surface
Atmosphere
Long-wave
radiation
Long-wave
radiation
Surface
