Indian Agricultural: Growth, Generation, Policy & Problem Indian Agricultural | Page 52

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dry winds that blow during the day in India. Direct exposure to these winds may be fatal. In cooler
regions of North India, immense pre-monsoon squall-line thunderstorms, known locally as "Nor
‘westers", commonly drop large hailstones. In Himachal Pradesh, Summer lasts from mid-April till the
end of June and most parts become very hot (except in alpine zone which experience mild summer)
with the average temperature ranging from 28 °C (82 °F) to 32 °C (90 °F). Winter lasts from late
November till mid-March. Snowfall is generally common in alpine tracts that are above 2,200 meters
(7,218 ft), especially those in the higher- and trans-Himalayan regions. Near the coast the
temperature hovers around 36 °C (97 °F), and the proximity of the sea increases the level of humidity.
In southern India, the temperatures are higher on the east coast by a few degrees compared to the
west coast.
By May, most of the Indian interior experiences mean temperatures over 32 °C (90 °F), while
maximum temperatures often exceed 40 °C (104 °F). In the hot months of April and May, western
disturbances, with their cooling influence, may still arrive, but rapidly diminish in frequency as summer
progresses. Notably, a higher frequency of such disturbances in April correlates with a delayed
monsoon onset (thus extending summer) in northwest India. In eastern India, monsoon onset dates
have been steadily advancing over the past several decades, resulting in shorter summers there.
Altitude affects the temperature to a large extent, with higher parts of the Deccan Plateau and other
areas being relatively cooler. Hill stations, such as Ootacamund ("Ooty") in the Western Ghats and
Kalimpong in the eastern Himalayas, with average maximum temperatures of around 25 °C (77 °F),
offer some respite from the heat. At lower elevations, in parts of northern and western India, a strong,
hot, and dry wind known as the loo blows in from the west during the daytime; with very high
temperatures, in some cases up to around 45 °C (113 °F); it can cause fatal cases of sunstroke.
Tornadoes may also occur, concentrated in a corridor stretching from northeastern India towards
Pakistan. They are rare, however; only several dozen have been reported since 1835.
Monsoon
The southwest summer monsoon, a four-month period when massive convective thunderstorms
dominate India's weather, is Earth's most productive wet season. A product of southeast trade winds
originating from a high-pressure mass cantered over the southern Indian Ocean, the monsoonal
torrents supply over 80% of India's annual rainfall. Attracted by a low-pressure region cantered over
South Asia, the mass spawns surface winds that ferry humid air into India from the southwest. These
inflows ultimately result from a northward shift of the local jet stream, which itself results from rising
summer temperatures over Tibet and the Indian subcontinent. The void left by the jet stream, which
switches from a route just south of the Himalayas to one tracking north of Tibet, then attracts warm,
humid air.
The main factor behind this shift is the high summer temperature difference between Central Asia and
the Indian Ocean. This is accompanied by a seasonal excursion of the normally equatorial
Ramesh Kumar P