At a glance
PaperPaper ISubjectGeographySyllabusIndian and World Geography: physical, social and economic aspects of geography pertaining to India and the WorldImportanceMedium
IndiaClimateClimatic RegionsKoeppenMonsoonPhysical Geography
India has a single broad monsoon climate, but within it lies a striking regional spread, from the perpetually wet Western Ghats and the rain-soaked north-east to the arid Thar and the cold deserts of Ladakh. CAPF tests the climatic-region question in two ways: the Koeppen classification codes (which letter goes with which region) and the descriptive type-to-region matching (tropical wet, semi-arid, mountain, and so on). It also tests the controlling factors (latitude, the Himalaya, altitude, distance from the sea, the monsoon) and a handful of extremes (the wettest and driest places). The treatment follows NCERT Class XI India: Physical Environment and G.C. Leong's Certificate Physical and Human Geography, and connects directly to indian monsoon and climate, where the monsoon mechanism itself is covered.
India's climate is shaped by a small set of controls:
- Latitude: the Tropic of Cancer (about 23.5° N) cuts the country roughly in half, so the south is tropical and the north is sub-tropical to temperate.
- The Himalaya: the wall blocks the cold central-Asian winter winds and forces the monsoon to shed its rain, giving India a far warmer and wetter climate than its latitude alone would suggest.
- Altitude: temperature falls with height (the normal lapse rate, about 6.5° C per km), so the mountains are cold while the plains at the same latitude are hot.
- Distance from the sea (continentality): the coasts have an equable, moderate climate; the interior (for example Delhi, Nagpur) has a large annual and daily temperature range.
- The monsoon and the pressure-and-wind reversal: the dominant control, bringing about three-quarters of the annual rainfall in the four months from June to September.
- Relief and the jet streams, the western disturbances (winter rain in the north-west), and the El Nino link, all of which modulate the pattern.
The German climatologist Wladimir Koeppen classified climates by temperature and rainfall, using letter codes. The first capital letter is the broad group, the second small letter the rainfall regime, and the third the temperature detail. For India the main types are:
| Koeppen code |
Type |
Where in India |
| Amw |
Tropical monsoon, short dry winter |
West Coast (Malabar), south of Goa, the wet Western Ghats |
| As |
Tropical with a dry summer |
Coromandel (south-east) coast, around the Tamil Nadu coast |
| Aw |
Tropical savanna (dry winter) |
Most of the peninsular interior, south of the Tropic |
| BShw |
Semi-arid steppe, hot |
The rain-shadow of the Western Ghats, parts of Punjab, Haryana, interior Deccan |
| BWhw |
Hot desert |
Western Rajasthan (the Thar) |
| Cwg |
Humid sub-tropical, dry winter (the Ganga type) |
The Northern Plains, the Indo-Gangetic belt |
| Dfc |
Cold humid winter (the taiga-type) |
The high north-east and the Himalayan foothill belt |
| E (ET / EF) |
Tundra and ice / polar |
The high Himalaya and the Trans-Himalaya (Ladakh, the high peaks) |
The codes worth fixing for the exam are: Amw (Malabar / west coast), As (Coromandel), Aw (peninsular interior savanna), BWhw (Thar desert), BShw (semi-arid), Cwg (Gangetic plain), and E (the high Himalaya).
The American geographer Glenn Trewartha modified Koeppen into simpler descriptive regions that CAPF also uses:
- Tropical rainy (the West Coast and north-east, heavy rain).
- Tropical wet and dry / savanna (the peninsular interior).
- Tropical semi-arid (steppe) (the rain-shadow and the Punjab plains).
- Tropical and sub-tropical desert (the Thar).
- Humid sub-tropical with dry winter (the Northern Plains).
- Mountain climate (the Himalaya, graded by altitude).
- The West Coast and the Western Ghats: the wettest part of mainland India, on the windward side of the south-west monsoon. Mawsynram and Cherrapunji in Meghalaya (in the funnel-shaped Khasi Hills) are among the wettest places on earth; Agumbe in Karnataka is "the Cherrapunji of the south".
- The north-east: very heavy monsoon rain, hill-station coolness with altitude.
- The Northern Plains (Cwg): hot summers, cool to cold winters (with western-disturbance rain in the north-west), monsoon rain decreasing from east (Bengal, over 100 cm) to west (Punjab and the Thar fringe).
- The Thar (BWhw): hot desert, very low and erratic rainfall (under 25 cm), extreme day-night temperature range.
- The peninsular interior (Aw): tropical savanna, moderate monsoon rain, a rain-shadow belt east of the Ghats.
- The Coromandel coast (As): rain mainly from the retreating (north-east) monsoon in October to December, so its wettest season is autumn-winter, unusual for India.
- The Himalaya and Trans-Himalaya: a vertical sequence from sub-tropical foothills up through temperate to alpine and the cold deserts of Ladakh and Spiti (in the rain-shadow north of the main range, very cold and very dry).
| Extreme |
Place |
Note |
| Wettest place |
Mawsynram (Meghalaya) |
Closely followed by Cherrapunji (Sohra); funnel of the Khasi Hills |
| Driest region |
Western Rajasthan / the Thar |
Under 25 cm; parts under 10 cm |
| Hottest recorded |
Phalodi / Churu region (Rajasthan) |
Verify the latest record |
| Coldest inhabited |
Dras (Ladakh) area |
Among the coldest inhabited places |
| Cold desert |
Ladakh, Spiti, Lahaul |
Rain-shadow, high-altitude arid |
The climatic regions map directly onto the disaster and deployment map that the CAPFs operate in. The cold deserts of Ladakh and the high Himalaya are the high-altitude, low-oxygen theatre where the ITBP and the Army hold the LAC, and where acclimatisation and frostbite are operational concerns. The wet north-east and the Brahmaputra valley face annual monsoon flooding, a recurring relief task. The semi-arid and desert belt of Rajasthan and Gujarat, guarded by the BSF, brings dust storms and extreme heat. The cyclone-prone east coast (Coromandel) draws the NDRF and the CAPFs into evacuation and relief. Climate change is widening these extremes, lengthening dry spells and intensifying rain events, which the disaster-management note develops further. See indian monsoon and climate and Index where relevant.
Formats: Koeppen-code-to-region matching (Amw, As, Aw, BWhw, Cwg, E); descriptive-type-to-region matching; the wettest and driest places; statement-based questions on why the Coromandel coast gets its rain in winter; and the controlling factors (the role of the Himalaya and continentality).
Authored practice (not verbatim PYQs):
Q1In the Koeppen scheme, the hot desert climate of western Rajasthan is coded:
- AAw
- BBWhw
- CCwg
- DAmw
Answer:
- B. BWhw is the hot desert type; the Thar lies in it.
Q2The Coromandel (south-east) coast receives most of its rainfall in:
- AJune to September
- BOctober to December
- CMarch to May
- DJanuary to February
Answer:
- B. It is fed mainly by the retreating north-east monsoon in October to December.
Q3The wettest place in India is generally taken to be:
- AAgumbe
- BCherrapunji
- CMawsynram
- DMahabaleshwar
Answer:
- C. Mawsynram in Meghalaya, closely followed by Cherrapunji.
Q4The Koeppen code Cwg in India denotes the climate of the:
- AWest Coast
- BNorthern Plains (Gangetic belt)
- CThar
- Dhigh Himalaya
Answer:
- B. Cwg is the humid sub-tropical dry-winter type of the Northern Plains.
Q5The cold deserts of Ladakh and Spiti are arid mainly because they lie:
- Aunder the subtropical high
- Bin the rain-shadow north of the Great Himalaya
- Con a cold ocean current
- Dat the equator
Answer:
- B. They sit in the rain-shadow behind the main Himalayan range, beyond the monsoon's reach.
- Koeppen codes: Amw (Malabar / west coast, monsoon), As (Coromandel, dry-summer), Aw (peninsular savanna). Do not swap Amw and As.
- The wettest places (Mawsynram, Cherrapunji) and the driest (the Thar) are both in India and often paired in a single question.
- The Coromandel coast's wet season is the retreating monsoon (October to December), not the south-west monsoon.
- Cold desert (Ladakh, rain-shadow and altitude) versus hot desert (Thar, subtropical aridity). Both are arid, for different reasons.
- The Himalaya warms India (blocking cold winds) and wets it (forcing rain); it does both.
- Koeppen India codes: "A-tropics, B-dry (Thar), C-Gangetic, E-Himalayan ice."
- Coromandel: "South-East coast, October rain (retreating monsoon)."
- Cold desert: "Ladakh is dry because the Himalaya stole its rain."
- Wettest: "Mawsynram first, Cherrapunji second, both in Meghalaya."
- India's controls: latitude, the Himalaya, altitude, continentality, and the monsoon.
- Koeppen for India: Amw (west coast), As (Coromandel), Aw (peninsular savanna), BWhw (Thar), BShw (semi-arid), Cwg (Gangetic plains), E (high Himalaya).
- The West Coast and north-east are the wettest; the Thar is the driest.
- Mawsynram is the wettest place, just ahead of Cherrapunji, both in Meghalaya.
- The Coromandel coast is fed by the retreating north-east monsoon (October to December).
- The cold deserts of Ladakh and Spiti are arid by rain-shadow and altitude.
- India has one broad monsoon climate with strong regional variation.
- The Himalaya both warms India (blocking cold winds) and wets it (forcing monsoon rain).
- Koeppen codes for India: Amw (west coast), As (Coromandel), Aw (peninsular savanna), BWhw (Thar desert), BShw (semi-arid), Cwg (Gangetic plains), E (high Himalaya).
- The West Coast and the north-east receive the heaviest rain; the Thar the least.
- Mawsynram and Cherrapunji in Meghalaya are among the wettest places on earth.
- The Coromandel coast's wettest season is October to December (the retreating monsoon).
- Ladakh, Spiti and Lahaul are high-altitude cold deserts in the rain-shadow of the Himalaya.
- The Tropic of Cancer divides tropical south India from sub-tropical north India.
- The CAPFs operate across all these regimes, from the cold deserts of the LAC to the cyclone-prone east coast.
- Koeppen classification: a climate scheme using temperature and rainfall, with letter codes.
- Amw / As / Aw: tropical monsoon, tropical dry-summer, and tropical savanna types.
- BWhw / BShw: hot desert and semi-arid steppe types.
- Cwg: humid sub-tropical climate with a dry winter (the Gangetic type).
- Continentality: the effect of distance from the sea, giving a large temperature range.
- Rain-shadow: the dry leeward side of a mountain barrier.
- Cold desert: a high-altitude arid region (Ladakh, Spiti) made dry by rain-shadow and cold.
- Retreating monsoon: the north-east monsoon of October to December, which waters the Coromandel coast.
- Western disturbance: a winter cyclonic system from the Mediterranean that brings rain to the north-west.