Indian Monsoon Mechanism
Complex weather system driven by differential heating of land and sea, shifting of ITCZ, and upper air circulation (Jet Streams).
01
Thermal Concept
Halley's Theory: Differential heating causes low pressure over land (Summer) drawing winds from high pressure sea.
02
ITCZ Shift
Inter-Tropical Convergence Zone shifts north to Ganga plain in summer (Monsoon Trough), pulling South East Trade Winds across equator.
03
Jet Streams
Sub-Tropical Westerly Jet withdraws from north India. Tropical Easterly Jet sets in, steering depressions.
04
El Nino & La Nina
El Nino (warming of Peru coast) generally weakens monsoon. La Nina (cooling) strengthens it. IOD (Indian Ocean Dipole) also impacts.
05
Onset & Withdrawal
Bursts on Malabar coast (June 1). Branches: Arabian Sea & Bay of Bengal. Retreats by September-October (Retreating Monsoon).