Question.
What are Jet streams and how do they affect the climate of India?
( Chapter - 4 Climate, Cass 9 NCERT Contemporary India -I )
Answer.
Jet streams are high-altitude winds that blow in the troposphere about 12 km above the surface. It is a narrow belt of high-altitude winds.
The speed of jet streams is 110 km/h in summer and 184 km/h in winter.
There are two jet streams that affect the climate of India:
- subtropical westerly jet streams
- subtropical easterly jet streams
Role of subtropical westerly jet streams in the climate of India:
Generally, the subtropical westerly jet stream flows throughout the year from about 25 to 30 degrees north latitude, south of the Himalayas, except in summer.
In winter, the subtropical westerly jet stream is responsible for western disturbances and winter rainfall over the northern and northwestern parts of India.
In the summer season, the subtropical westerly jet streams shift from the south of the Himalayas to the north of the Himalayas; This movement of the westerly jet streams is responsible for bringing the monsoon [onset of the monsoon] winds closer to the Himalayas.
Role of subtropical easterly jet streams:
Subtropical easterly jet streams blow over peninsular India, about 14° latitude, only during the rainy season. This helps in the formation of depressions in the Bay of Bengal and helps in a more uniform distribution of monsoon rainfall across the Indian subcontinent.
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