Southwest monsoon season
Also called: Rainy season · Topic: Climate of India and the Monsoon · NCERT: Class 11, Ch 4 "Climate"
Meaning
The southwest monsoon season lasts from June to September. Intense heat creates a strong low over northwest India. This low pulls the southern trade winds across the equator. The Coriolis force, the turning effect of Earth's spin, bends them so they arrive from the southwest. They pick up moisture over warm seas and reach India as two branches: the Arabian Sea branch and the Bay of Bengal branch.
Rain starts suddenly with thunder and lightning. This is called the burst of the monsoon. Day temperatures fall by 5-8°C. The season brings about three-quarters of India's yearly rain. It decides kharif crops, reservoir levels and food prices.
Example
The monsoon normally reaches Kerala on 1 June and Mumbai and Kolkata on 10-13 June. Under IMD's 2020 revised normal dates, it covers the whole country by about 8 July.
Don't confuse with
- Northeast monsoon: this blows from land to sea in October-December. It picks up moisture over the Bay of Bengal and mainly wets the Tamil Nadu coast, not the whole country.
Related concepts
- Arabian Sea branch of the monsoon
- Rain shadow area
- Bay of Bengal branch of the monsoon
- Mawsynram
- Cherrapunji
- Dry Tamil Nadu coast in the southwest monsoon
- Break in the monsoon
- Monsoon depression