Why does Tamil Nadu coast achieve winter rainfall?

The geographical location of Tamil Nadu, the east coast receives rainfall as the northeast trade winds blow from the sea to land in this location, and because of this Tamil Nadu receives winter rainfall.

Monsoon in India and Tamil Nadu

From early June to mid-September is the duration of the monsoon. Most parts of the country get rainfall in this period. South India typically gets rainfall from southwest monsoons due to extreme South-West trade winds blowing to the northern hemisphere.

During the summer, as the land gets heated up, central India turns into a low-pressure region while the waters of the Arabian Sea turn into a high-pressure region. Winds blew from the high-pressure region to the low-pressure region. So, these winds move from the Arabian Sea to land, thus carrying moisture in the form of monsoon clouds called the South-West monsoon. However, these monsoons emerging from the Arabian Sea get hindered by the Western Ghats. These western ghats which expand from South Gujarat to South Tamilnadu block the clouds resulting in the clouds losing their moisture. This turns rainfall in the Western Ghats. Tamilnadu being in the rain shadow area of Western Ghats does not receive rainfall from these monsoons.

Reasons Why Tamilnadu Receives Rainfall in Winter

The reversal of the South West Monsoon winds is known as the North-East Trade Winds. The weakening of the heat flow over North-west India kicks off the North East Monsoon’s dynamics. This weakens the South-West Trade winds.

In the meantime, when the Sun moves south of the equator following the equinox on September 21( the date on which day and night are approximately equal length), the inside of India, especially Bihar, Jharkhand, and Bengal, cools quickly. Subsequently, high-pressure regions form over the North Bay of Bengal and northern India.

The winds are being pushed down south, towards India’s southeast coast, by this high-pressure region. Following that, a U-shaped low-pressure trough forms across India’s southern coast, which incorporates Tamil Nadu. The winds from the high-pressure region in the North Bay of Bengal are pulled by this low-pressure trough, bringing about the North-East monsoon. This is known as a Monsoon Retreat because the wind direction and situating of low and high-pressure zones are totally different from that of the southwest monsoon season. Subsequently, the coast of Tamil Nadu gets monsoons during winter due to North-East trade winds.

Related Links

1. Rainfall in India
2. Monsoon in India
3. Southwest Monsoon and Northeast Monsoon
4. Monsoon and Uncertainities

Frequently Asked Questions

Q 1. For what reason does Tamil Nadu get less rainfall during monsoon?

Answer-

Tamil Nadu gets exceptionally less rainfall through the southwest monsoon because Western ghats block the monsoon winds from blowing over the state.

Q 2. Why does Tamil Nadu get rainfall two times per year?

Answer-

During monsoons, Tamilnadu gets rainfall from South-West winds blowing to the northern hemisphere. But due to geographical reasons, during winter it gets rainfall from North-East winds.

Q 3. Where do the northeast trade winds come from?

Answer-

Northeast trade winds originate more from the direction of the poles in the Northern Hemisphere while southeast trade winds in the Southern Hemisphere.