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Indian Monsoon Explained: Mechanism, El Nino & Impact

Introduction

The term 'Monsoon' comes from the Arabic word 'Mausim'. It refers to the seasonal reversal of winds. For India, it is the lifeline, as agriculture (15% of GDP but 50% of employment) depends on it.

1. Mechanism

• Classical Theory (Halley): Differential heating of land and sea. In summer, land heats up, low pressure creates, pulling winds from high-pressure sea.
• Modern Theory (Flohn): Shift of Inter-Tropical Convergence Zone (ITCZ). As the sun moves north, ITCZ shifts over the Ganga plain, pulling Trade Winds which cross the equator, become SW Monsoon winds.

2. Teleconnections

• El Nino (The Little Boy): Warming of Peru Current in Pacific. Weakens Indian Monsoon.
• La Nina (The Little Girl): Cooling of Pacific. Good for Indian Monsoon.
• Indian Ocean Dipole (IOD): Positive IOD (warmer Western Indian Ocean) is good for monsoon; Negative IOD is bad.

Conclusion

Monsoon is the "Real Finance Minister" of India. Understanding its vagaries is crucial for food security.