Geoscience Reference
In-Depth Information
radiation is assumed to be constant throughout the day
and so does not add to the spatial variability of solar
receipt at the surface. None the less it is vitally important
for slopes with a northerly aspect or very shaded locations,
which would otherwise receive very little short-wave
radiation. Moon explorers were able to see this, for with
no atmosphere there is no diffuse radiation and any
surface that is not directly in sunlight appears dark.
These effects of slopes upon radiation inputs mean that
the radiation balance varies locally with topography. In the
northern hemisphere, slopes with a southerly aspect
receive a greater input of radiation than horizontal and
northerly ones, resulting in larger exchanges in sensible
heat and higher temperatures (
Table 8.5,
and p. 601
). In
high latitudes this additional energy may be an advantage,
but in more arid countries the increased radiation will
evaporate moisture more quickly and may produce even
greater moisture stresses in plants.
D
30
25
20
SE / SW
W / E
S
15
NE / NW
10
N
5
0
0 0 0 0 0 0 0 0 0 °
Slope
E
25
20
S
15
SE / SW
Orientation
After five
After two
10
dry days
rain days
W / E
Maximum temperature
N
5
NE / NW
N
-1·9
-1·5
E
-1·3
0·0
0
S
2·6
1·4
0
10
20
30
40
50
60
70
80
90°
Slope
W
0·5
0·2
F
Minimum temperature
N
8
S
-0·3
-0·4
E
-0·1
-0·4
6
SE / SW
S
0·4
0·3
W
0·0
0·5
4
Daily mean temperature
N
-0·9
-0·4
E
0·1
-0·3
2
W / E
S
1·1
0·6
N / NE / NW
W
-0·4
0·2
0
0
10
20
30
40
50
60
70
80
90°
Relative humidity at 13.00 (%)
N
Slope
8
1
E
3
5
incident upon slopes of differing angle and aspect at 53°N for
(a) 21 June, (b) 22 March-22 September and (c) 21 December.
Note different scales.
Source: Based on a model developed by the Department of Building
Science, University of Sheffield
S
-13
-3
W
6
-4
Source: Translated from Fuh, Baw-Puh (1962).
Note: Figures are relative to a horizontal surface near by.
