🌧️ Climate of India
Monsoon, seasons, rainfall, and India's climate regions.
🌧️ The Indian Monsoon
India has a tropical monsoon climate. The word "monsoon" comes from the Arabic word mausim meaning "season." The entire agricultural economy of India depends on the monsoon.
4 Seasons of India (IMD classification):
1. Cold Weather Season (Dec–Feb) — Temperature drops, western disturbances bring rain to NW India. Snowfall in Himalayas.
2. Hot Weather Season (Mar–May) — Temperatures rise to 45°C+. Loo winds blow in NW India. Dust storms (andhi) in Rajasthan.
3. Advancing Monsoon / SW Monsoon (Jun–Sep) — Brings ~75% of India's annual rainfall. Life-giving but also causes floods.
4. Retreating Monsoon / NE Monsoon (Oct–Nov) — As SW monsoon withdraws, NE monsoon brings rain to Tamil Nadu and SE coast.
Why does the monsoon happen?
By June, the land (especially Rajasthan) heats up intensely → creates a strong low pressure area. Moisture-laden winds from the cool Indian Ocean (high pressure) rush in to fill it. These are the South-West monsoon winds.
The SW Monsoon hits India as two branches:
1. Arabian Sea Branch — hits Kerala first (June 1), moves north along Western Ghats (very heavy rain on windward/west side), crosses Vindhyas, reaches Delhi by end of June.
2. Bay of Bengal Branch — moves north along the Bengal coast, gives heavy rain to NE India (Meghalaya gets world's highest rainfall!), turns west across the Ganga plains.
The two branches merge over the Ganga plains, making this region receive rainfall from both branches!
In winter (Dec–Feb), western disturbances are extra-tropical cyclones originating in the Mediterranean Sea. They travel east along the jet stream and bring rain/snow to northwestern India (Punjab, Haryana, UP, HP, J&K).
This winter rain (mahawat) is crucial for rabi crops (wheat, mustard, gram). Without western disturbances, NW India would be a desert year-round.
The Monsoon Journey Across India
AnimationKerala gets the monsoon first (June 1). The entire country is covered by late July.
India's Climate Regions
Interactive1. Funnel-shaped topography: The Khasi Hills form a funnel/bowl shape that channels the Bay of Bengal monsoon winds upward
2. Orographic rainfall: As the moist winds rise, they cool and condense — releasing enormous amounts of rain. This is called "relief rainfall"
3. Location: Directly in the path of the Bay of Bengal branch of the SW monsoon
4. No barrier to the south: The Bay of Bengal is directly to the south — unobstructed moisture supply
However, Mawsynram is extremely dry for 4-5 months — most rain falls in just 3-4 months of monsoon season.
1. Latitude: Tropic of Cancer passes through India — south is tropical, north is subtropical. Southern India stays warm year-round.
2. Altitude: Higher areas are cooler (Himalayas, Deccan plateau cooler than plains). Temperature decreases 6.5°C per 1000m rise.
3. Pressure and Winds: SW monsoon winds bring rain. Northeast trade winds cause dry season in most of India. Western disturbances bring winter rain to NW India.
4. Distance from Sea (Continentality): Coastal areas have moderate, humid climate. Interior India has extreme temperatures (hot summers, cold winters).
5. Ocean Currents: Warm currents near Kerala coast contribute to heavy rainfall. Indian Ocean = warm = more evaporation = more rain.
6. Relief (Topography): Western Ghats cause heavy rain on windward west side but rain-shadow (dry) on east side (parts of Karnataka/AP). Himalayas block cold winds from Central Asia — keeping India warmer than similar latitudes elsewhere.