The monsoon winds are caused by the differential heating and cooling of the land and the sea. They are divided into two systems—summer monsoon and winter monsoon. In this article, you will learn the Phenomenon and Mechanism of the Monsoons.
Phenomena and Mechanism of the Monsoons
Summer Monsoon
- The land heats quickly during summers, and hence, low-pressure conditions develop over the land. As the sea is relatively cool, a high-pressure area develops over the sea.
- Because winds move from a high-pressure area to a low-pressure area, winds move from the sea to the land. This is called the summer monsoon.
- In May, June, and July, the plains of the Indian subcontinent receive vertical rays of the Sun. While a low-pressure area develops over the land, a high-pressure area develops over the sea.
- Thus, winds blow from the Indian Ocean northwards and northwestwards into Asia. Because they blow from the southwest, they are known as the southwest summer monsoon.
Winter Monsoon
- During the winter, oceans tend to become warm and the land cools down. A high-pressure area develops over the land and a low-pressure area develops over the Indian Ocean.
- The winds move from a high-pressure area to a low-pressure area. Thus, the winds which blow from the land to the sea are dry and are devoid of any moisture. They bring cold weather and do not produce any rainfall.
- When these winds blow over adjoining oceans, they pick up moisture and bring rainfall over the southern Coromandel Coast (coastal Tamil Nadu) and over the southern tip of Andhra Pradesh.
- Because these winds blow from the northeastern parts of the country, they are also known as northeast monsoon winds.
Features of Rainfall in India
- Rainfall in India is mainly concentrated to the months of July, August and September.
- In India, the rainfall is mainly orographic in nature. The places located on the windward side receive more rainfall than the places located on the leeward side.
- Only a small amount of rainfall is received from cyclones and convectional rainfall. 4. Monsoon in India is erratic, uneven and unpredictable. While there are floods in some regions, the other regions experience drought.
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