Question

Which of the following is/are true about Jet streams?

1. These are high velocity winds that blow in the upper troposphere.
2. Jet streams does not have any influence on Indian monsoon.

[1 mark]

• A. Only 1
• B. Only 2
• C. Both 1&2
• D. Neither 1 nor 2

Answer 1

The correct option is A Only 1

Jet streams are high velocity winds that blow in the upper troposphere at an altitude of around 12,000 metres.
These winds are faster than surface winds as there are no obstacles in the upper troposphere. The speed can vary from 110 to 184 km/h in winter.
Southern branch of one particular jet stream located approximately over 27° to 30° north latitude, also known as the subtropical westerly jet stream, has influence on the indian monsoon. Jet streams intensify high pressure conditions. As long as these high pressure conditions prevail, winds flow from the northeast direction, from land to sea. And till such conditions persist, the onset of monsoon will be delayed. But during the month of June, the southern branch of the jet stream shifts northwards. As soon as the southern branch of the jet stream disappears, a low pressure zone appears over the Indian subcontinent attracting the monsoon winds from the southwest, from sea to land, thereby beginning the monsoon season.