Question

Monsoon is caused by

• A. Movements of cloud
• B. Impact of Summer temperature on the sea
• C. Rise in temperature
• D. Seasonal reversal of winds

Hint:

Recall that land and sea heat unevenly through the year, and this difference flips the wind direction each season.

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
The question asks for the basic cause behind the monsoon, the seasonal rain bearing wind system over regions like India.

Step 2: Key Formula or Approach:
A monsoon is defined in geography as a wind system that reverses direction between summer and winter, and this reversal is what brings and then withdraws the rains.

Step 3: Detailed Explanation:
In summer, land heats up faster than the sea, so a low pressure area forms over the Indian subcontinent while the ocean stays relatively high pressure.
Moist air then flows from the sea towards the land, and this onshore flow is the south west monsoon that brings heavy rain.
In winter, the land cools down faster than the sea, so high pressure builds over land and low pressure over the ocean, and the wind direction flips to blow from land to sea, giving the dry north east monsoon.
Movements of cloud and a rise in temperature are effects that come along with this process, not the root cause, so options (A) and (C) only describe symptoms.
The impact of summer temperature on the sea in option (B) is only half the picture, since it ignores the matching change in pressure over land and the resulting reversal of wind direction.

Step 4: Final Answer:
The defining cause of monsoons is the seasonal reversal of wind direction, so option (D) is correct.