pakistan geographical review 1954 - University of the Punjab

There is a great difference in West and East Pakistan not only in the
annual amounts but also in the periodicity of rainfall. Over the plain of West
Pakistan and parts of the neighbouring highlands most of the rainfall takes place
in late summer and has a secondary winter or spring maximum, the latter being
very useful for the unirrigated Rabi crops like Wheat. In many parts of the
montain region, both in the north and west, the winter and spring rains become
more important than the summer rains as in Chitral-Swat (Drosh), Baltistan,
Gilgit, Quetta-Sarwan. Drosh (Chitral) has more rains in spring than in winter
while it is just the reverse at Quetta.
In East Pakistan the rainy season is longer. While like West Pakistan
most of the rainfall takes place in late summer during the prevalence of the
summer Monsoons, here the pre-Monsoon or early summer months are also
quite rainy. Also the rainy season is prolonged uptil October and even
November. Unlike West Pakistan December and January are generally the
driest months.
Thus taking the two wings together, the rainfall takes place in one part
or the other all the year round. It takes place in East Pakistan in such amounts
that make the cultivation of wettest crops possible. In West Pakistan, where
it is deficient, nature has partly compensated for it by providing big perennial
streams in the fertile plains. These streams are very nicely spaced where the
plain is broadest. Even minor plains are not without streams. Winter rains
in the hills and table-lands of West Pakistan introduce an element of Mediterranean
climate.
In East Pakistan the erlect of high rainfall is further intensified by the
inflow of enormous amounts of water which forms the run-off from the
neighbouring area. It is further strengthened ,by the low variability, from 15 to
30%. As compared with it the variability of rainfall in West Pakistan is 40
to 80%.
Humidity.
The climate of the whole of East Pakistan may be called humid.
Humidity is high practically throughout the year. No month has a humidity
less than 70% in any part of East Pakistan, while during the rainy season it is
generally over 80%.
In West Pakistrn the low rainfall, practically cloudless skies and high
temperatures considerably reduce the humidity of the country. Only in the
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