Geoscience Reference
In-Depth Information
Minicoy (1575mm)
8°N, 73°E
Madras (1245mm)
13°N, 85°E
mm
mm
300
300
200
200
100
100
0
0
J
FM
A
M
J
J
A
S O N D
J
FM
A
M
J
J
A
S O N D
mm
mm
Bombay
(2083mm)
19°N, 73°E
Chittagong
(2870mm)
22°N, 92°E
700
700
600
600
500
500
400
400
300
300
200
200
100
100
0
0
J
FM
A
M
J
J
A
S O N D
J
FM
A
M
J
J
A
S O N D
mm
mm
Kalat (229mm)
29°N, 67°E
Bikaner (305mm)
28°N, 73°E
200
200
100
100
0
0
J
FM
A
M
J
J
A
S O N D
J
FM
A
M
J
J
A
S O N D
Figure 11.20
Average monthly rainfall (mm) at six stations in the Indian region. The annual total is given
after the station name.
Source: Based on 'CLIMAT' normals of the World Meteorological Organization for 1931-1960.
confluence about 30
E over China,
beyond the area of subsidence in the immediate
lee of Tibet (see
Figure 11.18
). It is significant that
the mean axis of the winter jet stream over China
shows a close correlation with the distribution of
winter rainfall (
Figure 11.21
). Other depressions
affecting central and north China travel within
the westerlies north of Tibet or are initiated by
outbreaks of fresh cP air. In the rear of these
depressions are invasions of very cold air (e.g. the
buran blizzards of Mongolia and Manchuria). The
effect of such cold waves, comparable with the
northerlies in the central and southern United
States, is greatly to reduce mean temperatures
°
N, 105
°
(
Figure 11.22
). Winter mean temperatures in less-
protected southern China are considerably below
those at equivalent latitudes in India; for example,
temperatures in Calcutta and Hong Kong (both
at approximately 22.5
C
in January and 22°C and 15°C in February,
respectively.
°
N) are 19
°
C and 16
°
2 Spring
The key to change during this transition season is
again found in the pattern of the upper airflow. In
March the upper westerlies begin their seasonal
migration northward, but whereas the northerly
