Indian Climate

Notes

India has a tropical monsoon climate with great regional variety. The Tropic of Cancer divides the country into a tropical south and a subtropical north.

Factors controlling the climate

Latitude (the Tropic of Cancer passes through the middle) and altitude (the Himalaya and the plateaus).
Distance from the sea (continentality): coastal areas are equable; the interior has extremes.
Relief: the Himalaya block cold Central Asian winds and trap the monsoon; the Western Ghats cause orographic rainfall; the Aravallis lie parallel to the monsoon winds.
Monsoon winds, western disturbances, jet streams, ENSO and Indian Ocean Dipole, and tropical cyclones.

Seasons

Cold weather (December-February): clear skies, cool and dry in the north (10-15°C), mild in the south (24-25°C in Chennai); western disturbances bring winter rain to the north-west (good for wheat); north-east trade winds blow from land to sea; Tamil Nadu gets rain in the north-east monsoon.
Hot weather (March-May): temperatures rise to 45-48°C or more in the north-west; Loo (hot dry winds); local storms: Kalbaisakhi (Nor'westers) in Bengal, Bordoichila in Assam and mango showers in Kerala and Karnataka.
South-west monsoon (June-September): heavy rain; the burst of the monsoon; breaks.
Retreating monsoon (October-November): falling temperatures; "October heat"; cyclones on the east coast; rain in Tamil Nadu.

Extremes: hottest places in the north-west (Ganganagar, Churu, Banda); coldest inhabited places in Ladakh (Drass, Kargil); the wettest, Mawsynram; the driest, the Thar and Ladakh.

Climatic regions (Koppen): Amw (Malabar coast), As (Coromandel), Aw (peninsular savanna), BShw (semi-arid) and BWhw (hot desert), Cwg (Ganga plain), Dfc (Arunachal), ET (high Himalaya).

Unity and diversity: the monsoon gives the country its climatic unity; the variations in temperature and rainfall create diversity (e.g., Kerala vs Rajasthan).

Concerns: climate change (rising temperatures, heat waves, erratic and extreme rainfall, glacier melt, sea-level rise).

Key Points

Tropical monsoon climate; four seasons.
Controls: latitude, altitude, relief, monsoon winds, western disturbances, jet streams.
Hot weather: Loo, Kalbaisakhi, mango showers.
Cold weather: western disturbances bring rain to the north-west.
Koppen: Amw, As, Aw, BShw, BWhw, Cwg, Dfc, ET.

MCQs

Q1. The hot dry winds of north India in summer are called:
(a) Loo
(b) Mistral
(c) Foehn
(d) Chinook Ans:
(a).

Q2. The mango showers occur in:
(a) Bengal
(b) Kerala and Karnataka
(c) Assam
(d) Punjab Ans:
(b).

Q3. Winter rainfall in north-west India is caused by:
(a) The monsoon
(b) Western disturbances
(c) Tropical cyclones
(d) Jet streams only Ans:
(b).