Q. Consider the following statements regarding the mechanism of the Indian Southwest Monsoon:
1.A high-pressure area forms over northwest India in summer, pulling in monsoon winds.
2.Winds from the southern hemisphere cross the equator and turn into southwest monsoon winds.
3.A special wind current (easterly jet stream) near 15°N helps trigger the start of the monsoon.
Choose the correct option:
Answer: B
Notes:
Explanation
- During the months of April and May, the landmass over the Indian subcontinent, especially the northwestern plains, becomes highly heated due to vertical solar insolation.
- This heating results in the creation of a strong low-pressure system, not a high-pressure zone.
- The southeast trade winds originate in the Southern Hemisphere and normally blow from southeast to northwest. As they cross the Equator, they get deflected due to the Coriolis force, which changes their direction to the right in the Northern Hemisphere, causing them to blow from southwest to northeast. This deflection converts the southeast trades into the southwest monsoon winds.
- The subtropical westerly jet retreats in late May–early June, allowing the ITCZ to shift northward. This shift enables the tropical easterly jet (TEJ) to form around 15°N. TEJ marks the monsoon onset and enhances vertical uplift and moisture inflow over India.
Source: India Physical Environment (Class 11th NCERT)
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