Climate & Monsoon
Geography · जलवायु और मानसून
📋Quick Overview
India has a 'Tropical Monsoon' type climate. The word 'Monsoon' is derived from the Arabic word 'Mausim' meaning 'season'. India's climate is influenced by the Himalayas in the north and the Indian Ocean in the south. The Tropic of Cancer divides India into two climatic zones — tropical (south) and subtropical (north). India experiences four major seasons in a year.
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The Indian Meteorological Department (IMD) was established in 1875, headquartered in New Delhi. It is responsible for weather forecasting in India.
📖Four Seasons of India
| Season | Months | Key Features |
|---|---|---|
| Cold Weather (Winter) | December - February | NE trade winds blow, Western Disturbances bring rain to NW India, coldest month = January, Chennai gets rain from NE monsoon |
| Hot Weather (Summer) | March - May | Highest temp in NW India, Loo (hot dry winds) blow in NW plains, hottest month = May, Nor'westers/Kalbaisakhi in WB & Assam, Mango Showers in Kerala & Karnataka |
| SW Monsoon (Rainy) | June - September | SW monsoon brings 75% of India's rainfall, enters India through Kerala coast (1 June), two branches: Arabian Sea & Bay of Bengal, causes heavy rain across India |
| Retreating Monsoon (Autumn) | October - November | SW monsoon retreats, clear skies in N. India, cyclones in Bay of Bengal, NE monsoon gives rain to Tamil Nadu, 'October Heat' — high humidity |
📖South-West Monsoon — Two Branches
📝NE Monsoon & Special Phenomena
- •NE Monsoon (Oct-Nov): Gives winter rainfall to Tamil Nadu — Coromandel Coast
- •Tamil Nadu gets most rain in winter due to NE monsoon (not from SW monsoon)
- •Western Disturbances: Originate in Mediterranean Sea, bring winter rain to Punjab, Haryana, Delhi (good for Rabi crops)
- •El Nino: Warming of Pacific Ocean → weak monsoon, drought in India
- •La Nina: Cooling of Pacific Ocean → strong monsoon, excess rainfall in India
- •Indian Ocean Dipole (IOD): Temperature difference between western and eastern Indian Ocean affects Indian monsoon
- •Mawsynram (Meghalaya) = wettest place on Earth (annual avg ~11,871 mm)
- •Cherrapunji (Sohra) = second wettest, once held the record
- •Mango Showers: Pre-monsoon showers in Kerala & Karnataka that help ripen mangoes
📝Rainfall Distribution in India
| Rainfall Zone | Annual Rainfall | Areas |
|---|---|---|
| Heavy Rainfall | > 200 cm | Western Ghats, NE India, Andaman & Nicobar |
| Moderate Rainfall | 100-200 cm | Eastern plains, Western Ghats leeward, Odisha, WB |
| Low Rainfall | 50-100 cm | Deccan Plateau interior, Upper Gangetic plain, Punjab |
| Scanty Rainfall | < 50 cm | Western Rajasthan, Kutch, Ladakh, Leh |