How the seasonal reversal of winds brings India its monsoon rains, and how the country's climate is classified into regions.
The Indian monsoon results from the seasonal reversal of wind direction driven by differential heating of land and sea. In summer, the Indian landmass heats faster than the ocean, creating a low-pressure zone that draws in moisture-laden southwest monsoon winds from the Indian Ocean (June-September). In winter, the pattern reverses — the northeast monsoon (retreating monsoon) brings drier winds from land to sea, except over the Tamil Nadu coast, which receives rainfall from it via the Bay of Bengal branch.
Using the widely-used Köppen climate classification, India spans multiple zones — tropical monsoon climate along the coasts and northeast, semi-arid steppe climate in the Deccan interior, hot desert climate in western Rajasthan (Thar), and montane/highland climate across the Himalayan region — reflecting India's vast latitudinal and altitudinal range.
APPSC tests the two monsoon branches (Arabian Sea and Bay of Bengal), the northeast monsoon's Tamil Nadu exception, and matching Köppen zones to Indian regions.
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