CLIMATE
Although the country is in the monsoon region, it
is arid, except for the southern slopes of the Himalayas
and the sub-Mountainous tract which have a rainfall
from 76 to 127 cm. Balochistan is the driest part
of the country with an average rainfall of 21 cm.
On the southern ranges of the Himalayas, 127 cm. of
precipitation takes place, while under the lee of
these mountains (Gilgit and Baltistan) rainfall is
hardly 16 cm. Rainfall also occurs from western cyclonic
distrubances originating in the Mediterranean.
It is appreciable in the western mountains and the
immediate forelying area; hre the rainfall average ranges
from 27 to 76 cm. The contribution of these western
distrurbances to rainfall over the plains is about 4
cm. A large part of the precipitation in the northern
mountain system is in the form of snow which feeds the
rivers. The all-pervasive aridity over most of Pakistan,
the predominant influence on the life and habitat of
the people, coupled with the climatic rhythm, characteristic
of a monsoon climate, are conducive to homogeneity of
the land.
Seasons The four well-marked seasons in Pakistan are:-
(i) Cold season (December to March).
(ii) Hot season (April to June).
(iii) Monsoon season (July to September).
(iv) Post-Monsoon season (October and November).
The cold season sets in by the middle of December.
This period is characterised by fine weather, bracing
air-low humidity and large diurnal range of temperature.
Winter distrubances in this season accordingly cause
fairly widespread rain. Average mimimum and maximum
temperatures are 4 oC and 18 oC, though on occasions
the mercury falls well below freezing point. The winter
sun is glorious. The hot season is usually dry. Relative
humidity in May and June varies from 50 per cent in
the morning to 25 per cent or less in the afternoon.
The temperature soars to 40 oC and beyond. The highest
recorded temperature at Jaccobabad in June is 53 oC.
While the interior is blazing hot, the temperature along
the sea coast ranges between 25 oC to 35 oC, but the
humidity persists around 70 to 80 per cent.
The south-west monsoon reaches Pakistan towards the
beginning of July and establishes itself by the middle
of the month. The strength of the monsoon current increases
form June to July; it then remains steady, and starts
retreating towards the end of August, though occasionally,
it continues to be active even in September when some
of the highest floods of the Indus Basin have been recorded.
From the middle of September to the middle of November
is the transitory period which may be called the post-monsoon
season.
In October, the maximum temperature is of the order
of 34 oC to 37 oC all over Pakistan, while the nights
are fairly cool with the minimum temperature around
16 oC. In the month of November, both the maximum and
the mimimum temperatures fall by about 6 oC and the
weather becomes pleasant. October and November are by
far the driest months all over the plains of Pakistan.
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