World Climate Regions
World Climate Regions
Climate is the average weather conditions of a place over a long period (at least 30 years, as per the World Meteorological Organization). The world's climate is classified into distinct regions based on temperature, precipitation, and vegetation patterns. The most widely used classification systems are by Wladimir Köppen and C.W. Thornthwaite. Understanding global climate regions is essential for geography, agriculture, and environmental studies.
Key Dates
Wladimir Köppen published his first climate classification — later revised multiple times (final version 1936 with Rudolf Geiger)
Bergen School of Meteorology (Bjerknes, Norway) — developed polar front theory and air mass concept that explains climate patterns
C.W. Thornthwaite proposed climate classification based on potential evapotranspiration and moisture index — more dynamic than Köppen
Tropical Easterlies (Trade Winds) theory formalized — explains dry climates at 20-30° and monsoon reversal mechanisms
Glenn Trewartha modified Köppen system, adding a subtropical group (Cf/Cw) — widely used in modern geography
Five major groups: A (Tropical), B (Dry), C (Temperate), D (Continental), E (Polar) — subcoded by precipitation and temperature
India spans Aw (peninsular), Am (Malabar/NE), BWh (W Rajasthan), BSh (E Rajasthan), Cwa (Indo-Gangetic Plain), ET (Himalayas)
India's monsoon climate is unique — seasonal reversal of winds brings 75% of annual rainfall in June-September
Warm dry summers + cool wet winters (Csa/Csb) — Mediterranean basin, California, Chile, SW Australia, W Cape (South Africa)
El Nino-Southern Oscillation — most powerful climate pattern affecting tropical/subtropical climates globally; linked to Indian monsoon failures
IPCC (Intergovernmental Panel on Climate Change) established — assesses climate science and projections of climate zone shifts
IPCC AR6: climate zones shifting poleward at ~0.5° latitude/decade; tropical belt widening; extreme weather events increasing
Mawsynram (Meghalaya, India) — world's wettest place by average annual rainfall (~11,872 mm); nearby Cherrapunji held previous record
Köppen Climate Classification — The Foundation
Wladimir Köppen (1846-1940), a Russian-German climatologist, developed the most widely used climate classification system, first published in 1884 and refined until 1936 (with Rudolf Geiger). The system is empirical — based on observable data (temperature and precipitation) rather than causal mechanisms — and uses vegetation as an indicator of climate. It classifies climates into 5 major groups: A — Tropical Climates: All months have average temperature above 18°C; no winter; high rainfall. B — Dry (Arid and Semi-arid) Climates: Evaporation exceeds precipitation; defined by a precipitation threshold formula rather than temperature. C — Temperate (Mesothermal) Climates: Coldest month between -3°C and 18°C; at least one month above 10°C; distinct warm and cool seasons. D — Continental (Microthermal) Climates: Coldest month below -3°C; warmest month above 10°C; large annual temperature range; found only in the Northern Hemisphere (large landmasses needed). E — Polar Climates: Warmest month below 10°C; no true summer. Each group is subdivided using lowercase letters for precipitation patterns (f = no dry season, m = monsoon, w = dry winter, s = dry summer) and temperature characteristics (a = hot summer, b = warm summer, c = cold summer, d = very cold winter, h = hot, k = cold). India's climates under Köppen: most of peninsular India is Aw (tropical savanna with dry winter); the Malabar coast and northeast are Am (tropical monsoon); western Rajasthan is BWh (hot desert); eastern Rajasthan is BSh (hot semi-arid); the Indo-Gangetic Plain is Cwa (humid subtropical with dry winter); the Himalayas range from Cwa to ET (tundra).
Tropical Climates (Group A)
Tropical climates are found within approximately 23.5°N to 23.5°S latitude, characterized by year-round warmth (all months above 18°C) and high rainfall. Subtypes: (1) Af — Tropical Wet (Equatorial/Rainforest) Climate: No dry season; rainfall in every month exceeds 60 mm; annual rainfall 1,500-2,500+ mm; constant high temperatures (25-28°C); found in the equatorial belt — Amazon Basin (Brazil), Congo Basin (Africa), Indonesia, Malaysia, parts of Western Ghats and Northeast India (Meghalaya receives over 11,000 mm); supports tropical evergreen rainforests — the most biodiverse terrestrial biome; convectional rainfall dominant. (2) Am — Tropical Monsoon Climate: A short dry season (1-2 months with <60 mm rain) compensated by heavy rainfall in other months (annual total >1,500 mm); seasonal wind reversal (monsoon); found in India (Malabar coast, Northeast), Southeast Asia, parts of Central America, northern Australia; supports tropical monsoon forests (semi-evergreen and moist deciduous). (3) Aw — Tropical Savanna (Wet-Dry) Climate: Distinct wet and dry seasons; 3-8 dry months; annual rainfall 1,000-1,500 mm; found in India (most of peninsular India, Indo-Gangetic Plain), sub-Saharan Africa (the Sahel, East Africa), parts of South America and northern Australia; supports savanna grasslands and tropical dry deciduous forests; the Indian monsoon climate is predominantly Aw. The tropical belt supports about 40% of the world's population and produces most of the world's rice, sugarcane, rubber, cocoa, coffee, and tropical fruits. Tropical regions are most affected by cyclones and monsoon variability.
Dry Climates (Group B)
Dry climates are defined not by temperature but by moisture deficit — evaporation exceeds precipitation. They cover about 26% of the world's land area. Subtypes: (1) BWh — Hot Desert: Annual rainfall typically below 250 mm; extreme heat (summer maxima can exceed 55°C); large diurnal temperature range (up to 40°C day-night difference); sparse xerophytic vegetation (cacti, thorny bushes); found in the subtropical high-pressure belt (20-30° latitude): Sahara, Arabian, Thar, Kalahari, Sonoran, Great Australian deserts; trade wind deserts on the west coasts of continents (Atacama, Namib) are caused by cold ocean currents; the Thar Desert (Rajasthan) is a BWh climate with annual rainfall of 100-250 mm. (2) BWk — Cold Desert: Arid but with cold winters (coldest month below 0°C); found in continental interiors at higher latitudes: Gobi (Mongolia-China), Patagonia (Argentina), Karakum (Central Asia), parts of Ladakh (India); Leh receives only about 100 mm of rainfall annually with winter temperatures dropping to -30°C. (3) BSh — Hot Semi-arid (Steppe): Rainfall 250-500 mm; transitional between desert and humid climates; grassland (steppe) vegetation; found on the margins of hot deserts: Sahel (Africa), eastern Rajasthan and Gujarat (India), interior peninsular India; in India, parts of Maharashtra, Karnataka, Tamil Nadu (rain shadow areas) also qualify. (4) BSk — Cold Semi-arid: Semi-arid with cold winters; found in the Great Plains of North America, Central Asian steppes, and parts of Patagonia. Hot deserts are expanding — the Sahara has grown by about 10% since 1920, partly due to climate change. In India, desertification is spreading from western Rajasthan into adjoining regions.
Temperate and Continental Climates (Groups C and D)
Group C — Temperate (Mesothermal) Climates: Moderate temperatures; coldest month between -3°C and 18°C. Key subtypes: (1) Cfa — Humid Subtropical (no dry season, hot summer): Hot, humid summers; mild winters; year-round rainfall; found in southeastern USA, southeastern China, southeastern South America, parts of eastern Australia. (2) Cwa — Humid Subtropical (dry winter): Similar to Cfa but with a distinct dry winter; found in northern India (Indo-Gangetic Plain — Delhi, Lucknow, Patna), southeastern China, parts of southeastern Africa; India's most populous region falls under Cwa. (3) Cfb — Marine West Coast (Oceanic): Cool summers, mild winters; rainfall throughout the year; moderate temperatures moderated by ocean; found in Western Europe (UK, France, Netherlands), Pacific Northwest (USA-Canada), New Zealand, southern Chile; ideal for agriculture and human settlement. (4) Csa — Mediterranean (dry summer): Warm to hot, dry summers; mild, wet winters; found around the Mediterranean Sea (Italy, Greece, Spain, Morocco), California, central Chile, southwestern Australia, Western Cape (South Africa); famous for olive, grape, and citrus cultivation. Group D — Continental (Microthermal) Climates: Large annual temperature range; coldest month below -3°C; found only in the Northern Hemisphere (large landmasses needed). (1) Dfa/Dfb — Humid Continental: Hot or warm summers, cold winters; year-round precipitation; found in northeastern USA, southern Canada, and Eastern Europe. (2) Dfc/Dfd — Subarctic: Short, cool summers; very long, cold winters (Dfd: coldest month below -38°C — Verkhoyansk and Oymyakon in Siberia have recorded -68°C); supports taiga/boreal forests (the world's largest biome by area); found across Canada, Alaska, Scandinavia, and Siberia.
Polar and Highland Climates (Group E and H)
Group E — Polar Climates: Warmest month below 10°C; too cold for trees. Subtypes: (1) ET — Tundra: Warmest month between 0°C and 10°C; permafrost underlies the surface; supports only mosses, lichens, dwarf shrubs, and grasses during the brief summer; found in the Arctic fringes of North America, Europe, and Asia; also found at very high altitudes in the Himalayas (above 4,000 m in India) and on sub-Antarctic islands; in India, the uppermost Himalayan zones (parts of Ladakh, upper Sikkim, and Arunachal Pradesh above the tree line) have ET characteristics. (2) EF — Ice Cap: All months below 0°C; permanent ice and snow; no vegetation; found in Antarctica and interior Greenland; the coldest temperature recorded on Earth was -89.2°C at Vostok Station, Antarctica (1983). Highland Climates (H): Mountains create their own climatic zones due to altitude — temperature decreases by about 6.5°C per 1,000 m (normal lapse rate); rainfall patterns change with aspect (windward vs leeward); vegetation zones change with altitude (vertical zonation). The Himalayas demonstrate this dramatically: from tropical forests at the base (below 1,000 m) through subtropical, temperate, subalpine, and alpine zones to permanent snow (above 5,000-6,000 m). A journey from Haridwar (300 m) to Badrinath (3,100 m) to the Gangotri Glacier (3,750 m) and beyond is like traveling from the tropics to the Arctic. Highland climates are not separately classified in Köppen's system but are recognized in modified systems (e.g., Trewartha adds an H group). About 24% of the world's land area is mountainous, and highland climates affect about 12% of the global population.
Climate and Vegetation Biomes
Climate regions correspond closely to global vegetation biomes: (1) Tropical Rainforest (Af) — the most biodiverse biome; multi-layered canopy; Amazon, Congo, Southeast Asia; in India: Western Ghats, Andaman Islands, NE India. (2) Tropical Savanna (Aw) — grassland with scattered trees; seasonal rainfall; Africa (Serengeti), India (Deccan), South America (Cerrado). (3) Hot Desert (BWh) — sparse xerophytic vegetation; Sahara, Arabian, Thar, Kalahari. (4) Mediterranean (Csa) — sclerophyllous vegetation (chaparral, maquis); adapted to summer drought; olive, citrus, cork oak. (5) Temperate Grassland — prairies (North America), steppes (Eurasia), pampas (South America), veldt (South Africa); moderate rainfall; highly fertile soils (chernozems). (6) Temperate Deciduous Forest (Cfa/Cfb) — broadleaf trees that shed leaves in winter; moderate rainfall; oak, beech, maple; Eastern USA, Western Europe, Eastern China. (7) Taiga/Boreal Forest (Dfc) — coniferous forests (spruce, pine, fir, larch); the world's largest biome by area; Russia, Canada, Scandinavia; important for timber and carbon storage. (8) Tundra (ET) — treeless; mosses, lichens, dwarf shrubs; permafrost; Arctic fringes. (9) Ice Cap (EF) — no vegetation; permanent ice. India, despite occupying only about 2.4% of the world's land area, encompasses nearly all major biomes (except taiga and ice cap) due to its latitudinal range (8°N-37°N), altitudinal range (sea level to 8,611 m), and the influence of the monsoon system. The Western Ghats and Eastern Himalayas are among the world's 36 biodiversity hotspots.
Climate Change and Shifting Climate Zones
Human-induced climate change is causing climate zones to shift geographically: (1) Poleward Shift — tropical climates are expanding poleward as global temperatures rise; the tropical belt has widened by about 0.5° latitude per decade since 1979; subtropical dry zones are also expanding, pushing deserts poleward — the Sahara has expanded by about 10% since 1920. (2) Altitudinal Shift — climate zones in mountains are moving upward; the tree line in the Himalayas has shifted upward by 200-300 m over the past century; species adapted to cold, high-altitude conditions (like the snow leopard and Himalayan tahr) are being pushed to higher elevations with shrinking habitat. (3) Changes in Precipitation — the monsoon system is becoming more variable; some regions are getting wetter (more intense rainfall events), while others are getting drier; the Indian monsoon shows increased intensity of extreme rainfall events despite a declining trend in total seasonal rainfall. (4) Impact on Agriculture — shifting climate zones affect crop suitability; wheat cultivation in the Indo-Gangetic Plain is threatened by rising temperatures; coffee cultivation in the Western Ghats is being pushed to higher altitudes; tropical crop zones are expanding into formerly subtropical areas. (5) Impact on Ecosystems — biome shifts are occurring faster than many species can adapt or migrate; coral reef ecosystems are among the most vulnerable (bleaching above 1.5°C warming); boreal forests may shrink as tundra and grassland expand. The IPCC Sixth Assessment Report (AR6, 2021) projects that under a high-emissions scenario (SSP5-8.5), the tropical climate zone could expand by 8-10° latitude by 2100, fundamentally altering global agriculture, water resources, and biodiversity patterns. India's National Action Plan on Climate Change (NAPCC, 2008) addresses these shifts through eight missions covering solar energy, energy efficiency, sustainable agriculture, water, Himalayan ecosystems, green India, sustainable habitat, and strategic knowledge.
Thornthwaite Classification and Moisture Index
C.W. Thornthwaite's classification (1948) is more dynamic than Köppen's as it uses the concept of potential evapotranspiration (PE) — the amount of water that would evaporate and transpire if sufficient water were available. By comparing actual precipitation with PE, Thornthwaite calculates a moisture index that describes whether a climate is wet or dry relative to its water demand. His moisture index categories: Perhumid (>100), Humid (20-100), Moist Subhumid (0-20), Dry Subhumid (-33 to 0), Semi-arid (-67 to -33), and Arid (<-67). Thornthwaite's system accounts for the seasonal distribution of water surplus and deficit, which is critical for agricultural planning. Advantages over Köppen: (a) uses calculated water balance rather than arbitrary temperature thresholds; (b) applicable to agricultural and irrigation planning because it directly measures water availability for crops; (c) captures the "effectiveness" of precipitation — 500 mm of rain in a cool place with low evaporation is more effective than the same amount in a hot desert. India under Thornthwaite: the Malabar coast and NE India are perhumid; the Indo-Gangetic Plain is humid to moist subhumid; peninsular rain-shadow areas are dry subhumid; Rajasthan grades from semi-arid (east) to arid (west). For UPSC, the Thornthwaite system is less commonly directly tested but understanding the PE concept and moisture index is essential for answering questions on aridity, irrigation needs, and drought assessment. The Standardized Precipitation Index (SPI) used by IMD for drought monitoring is conceptually related to Thornthwaite's moisture approach.
Monsoon Climate — India's Unique System
The monsoon climate, found in South and Southeast Asia, is perhaps the most significant climate system for human civilization — nearly half the world's population depends on monsoon rains for agriculture and water. India's monsoon is classified as Am/Aw under Köppen. Key features of India's monsoon: (1) Seasonal Wind Reversal — the fundamental monsoon mechanism; during summer (June-September), low pressure over the heated Indian landmass (Thar Desert thermal low) draws moisture-laden winds from the Indian Ocean (southwest monsoon); during winter (October-March), high pressure over the cold continent drives winds from land to sea (northeast monsoon); this reversal is also driven by the differential heating between the Asian landmass and the Indian Ocean, amplified by the Tibetan Plateau's elevated heating. (2) Onset and Withdrawal — the southwest monsoon typically arrives in Kerala around 1 June (normal date), advances northwestward reaching Delhi by late June and the entire country by mid-July; withdrawal begins from NW India in September, completing by mid-December; the onset is marked by sudden increase in rainfall ("burst of the monsoon"). (3) Rainfall Distribution — India receives about 1,170 mm average annual rainfall; Mawsynram (Meghalaya, ~11,872 mm) vs Jaisalmer (~164 mm) — enormous variation; the Aravallis, Western Ghats, and Himalayan foothills create orographic rainfall on windward sides and rain-shadow areas on leeward sides; about 75% of total annual rainfall occurs in June-September. (4) El Nino Impact — El Nino (warming of equatorial Pacific) is statistically associated with below-normal Indian monsoon rainfall; 6 of India's worst droughts since 1950 occurred in El Nino years; La Nina (cooling of Pacific) tends to bring normal or above-normal monsoon. (5) Indian Ocean Dipole (IOD) — temperature difference between western and eastern Indian Ocean; positive IOD can partially compensate for El Nino's negative impact on the monsoon. (6) Madden-Julian Oscillation (MJO) — 30-60 day tropical atmospheric wave that causes active and break phases in the monsoon. IMD uses dynamical models (coupled ocean-atmosphere models) for seasonal monsoon forecasting — accuracy has improved significantly with numerical weather prediction.
ENSO, PDO, and Global Teleconnections
Climate patterns across the world are interconnected through teleconnections — distant atmospheric and oceanic linkages: (1) ENSO (El Nino-Southern Oscillation) — the most powerful year-to-year climate fluctuation; involves interaction between the tropical Pacific Ocean and atmosphere; El Nino phase: abnormal warming of equatorial eastern Pacific; weakens trade winds; suppresses Indian monsoon; causes drought in Australia, Indonesia; brings floods to Peru; La Nina phase: abnormal cooling of eastern Pacific; strengthens trade winds; often brings normal-good monsoon to India; ENSO Southern Oscillation Index (SOI) measures pressure difference between Tahiti and Darwin. (2) Indian Ocean Dipole (IOD) — discovered by Saji et al. (1999); measures sea surface temperature difference between western and eastern Indian Ocean; positive IOD: warming in western Indian Ocean → enhanced moisture supply to India → can offset El Nino's negative effect; negative IOD: can suppress monsoon even without El Nino. (3) Pacific Decadal Oscillation (PDO) — multi-decadal climate pattern in the North Pacific; positive PDO phase amplifies El Nino effects (combining with El Nino can cause severe Indian monsoon failures); negative PDO phase suppresses El Nino effects. (4) North Atlantic Oscillation (NAO) — pressure difference between Iceland Low and Azores High; influences European weather and has teleconnections with the Indian monsoon through upper-level atmospheric waves. (5) Jet Streams and Climate — the subtropical westerly jet stream shifts northward in summer (influenced by Tibetan Plateau heating), allowing the monsoon trough to establish over India; any disruption to this shift weakens the monsoon; the Tropical Easterly Jet (TEJ) during monsoon months is linked to monsoon intensity. These teleconnections are critical for understanding: why the Indian monsoon fails (drought years — 1987, 2002, 2009, 2014, 2015 were El Nino years), why extreme rainfall events occur (Chennai 2015 — positive IOD contributed), and why global climate change projections for the monsoon are uncertain (IPCC models disagree on whether future monsoons will strengthen or weaken, though most project increased variability and more extreme events).
Microclimates, Urban Climate, and Local Variations
Global climate classifications describe large-scale patterns, but local conditions create microclimates — small-scale climate variations within a broader climate zone: (1) Urban Microclimates — cities create their own microclimates distinctly different from surrounding rural areas: Urban Heat Island (UHI) effect makes cities 2-8 degrees Celsius warmer (concrete, asphalt, vehicle emissions, AC exhaust, reduced vegetation); Delhi's UHI intensity reaches 8 degrees Celsius on calm winter nights; urban areas generate more convective rainfall (cities can receive 5-25% more rainfall than surrounding rural areas — the "urban rainfall enhancement" effect observed over Mumbai, Bengaluru, and Hyderabad); wind patterns are modified (buildings create wind tunnels and calm zones). (2) Mountain Microclimates — altitude creates rapid climate changes with elevation: lapse rate of about 6.5 degrees Celsius per 1,000 m means that a 3,000 m mountain in tropical India can have a summit temperature 19.5 degrees Celsius cooler than its base; windward slopes receive more rain (orographic rainfall) than leeward slopes (rain-shadow — Pune receives 600 mm while Mahabaleshwar 100 km away receives 6,000+ mm); aspect (direction of slope) matters: south-facing slopes in the Himalayas receive more solar radiation and are warmer than north-facing slopes. (3) Water Body Effect — large water bodies moderate nearby temperatures: Mumbai (coastal, maritime influence) has a smaller temperature range (19-35 degrees Celsius) than Nagpur (inland, similar latitude: 13-46 degrees Celsius); the Great Lakes in North America create "lake-effect snow" on downwind shores. (4) Forest Microclimates — forests are cooler (by 3-5 degrees Celsius), more humid, and have reduced wind compared to open areas; deforestation thus changes local climate, increasing temperature extremes and reducing rainfall recycling. (5) Valley Microclimates — cold air drainage at night creates temperature inversions in valleys (valley floors are colder than hillsides); this causes frost damage to crops in Himalayan valleys; Dras (Ladakh) is one of the coldest inhabited places partly due to cold air pooling. Understanding microclimates is essential for: agriculture (crop selection, frost management), urban planning (heat mitigation), and environmental conservation (species habitats).
Climate Extremes — Records and Disaster Impact
Global and Indian climate extremes are frequently tested in competitive exams: (1) Temperature Records — Hottest recorded: Death Valley, California (56.7 degrees Celsius, 10 July 1913); India's hottest: Phalodi, Rajasthan (51.0 degrees Celsius, 19 May 2016); Coldest recorded: Vostok Station, Antarctica (-89.2 degrees Celsius, 21 July 1983); India's coldest: Dras, Ladakh (-60 degrees Celsius estimated; Dras is among the coldest inhabited places in the world). (2) Rainfall Records — Wettest place (average annual): Mawsynram, Meghalaya (~11,872 mm); Wettest in single year: Cherrapunji, Meghalaya (26,471 mm in 1860-61); Highest 24-hour rainfall: Foc-Foc, La Reunion (1,825 mm, 7-8 January 1966); India's highest 24-hour: Cherrapunji (1,563 mm, 15 June 1995); Driest inhabited place: Arica, Chile (0.76 mm average); India's driest: Leh, Ladakh (~100 mm). (3) Recent Climate Extremes in India — heat waves are becoming more frequent and intense (2023 April: record heat across India); cyclone intensity increasing (Cyclone Amphan 2020, Tauktae 2021, Biparjoy 2023 were all extremely severe); extreme rainfall events (Mumbai 2005: 944 mm in 24 hours; Chennai 2015: 494 mm in 24 hours; Kerala 2018: unprecedented state-wide flooding); glacier-related events (Chamoli 2021: rock-ice avalanche). (4) India's Vulnerability — India is ranked among the most climate-vulnerable countries: 80% of districts are vulnerable to extreme weather events; economic losses from extreme weather average Rs 20,000-30,000 crore annually; IPCC AR6 projects: Indian monsoon will become more variable, heat waves more frequent and longer, and coastal flooding will increase. (5) Climate adaptation in India — National Adaptation Fund for Climate Change (NAFCC, 2015); State Action Plans on Climate Change (SAPCCs) in all states; National Disaster Management Authority (NDMA) guidelines for heat waves, floods, cyclones, and earthquakes. Understanding climate extremes connects physical geography with disaster management — a cross-cutting theme in UPSC GS-I (geography) and GS-III (disaster management).
India's Climate Regions — Detailed State-wise Classification
India's vast latitudinal (8 degrees N to 37 degrees N), altitudinal (sea level to 8,611 m), and monsoon-influenced range creates remarkable climate diversity within a single country. Detailed regional climates: (1) Western Rajasthan (BWh — Hot Desert) — annual rainfall 100-250 mm; extreme temperatures (summer: 50 degrees Celsius, winter: near 0 degrees Celsius); diurnal range exceeds 20 degrees Celsius; sandstorms (Loo) in summer. (2) Eastern Rajasthan and Gujarat interior (BSh — Hot Semi-arid) — rainfall 300-500 mm; transition between desert and humid; supports rainfed millets and pulses. (3) Indo-Gangetic Plain (Cwa — Humid Subtropical with dry winter) — Delhi: average temperature 25 degrees Celsius, rainfall 617 mm, extreme summer (45+ degrees Celsius) and cool winter (near 0 degrees Celsius in January); Punjab-Haryana: similar but with cold fog in winter; Bihar-eastern UP: more humid (1,000-1,200 mm rainfall). (4) Western Ghats Windward (Am/Af — Tropical Monsoon/Equatorial) — Kerala, Konkan, and Malabar coast receive 2,500-5,000 mm rainfall; heavy orographic rainfall; near-equatorial temperatures (minimal seasonal variation). (5) Rain-shadow Peninsular India (Aw — Tropical Savanna) — interior Maharashtra, Karnataka, Telangana, AP: 500-1,000 mm rainfall; distinct wet (June-October) and dry (November-May) seasons; drought-prone areas. (6) Tamil Nadu Coast — unique among Indian climates: receives bulk rainfall from northeast monsoon (October-December) rather than southwest monsoon; Chennai gets 1,400 mm, mostly October-December. (7) Northeast India (Am/Af with highland variations) — Cherrapunji/Mawsynram receive 10,000-12,000 mm; Assam valley: hot humid (2,000-3,000 mm); hills of Meghalaya, Manipur, Mizoram: cooler, very wet. (8) Himalayas — vertical climate zonation: Sub-Himalayan (Cwa), Lesser Himalayas (Cfb — temperate), Greater Himalayas (Dfc — subarctic), Trans-Himalayas (BWk/BSk — cold desert in Ladakh and Spiti). (9) Andaman & Nicobar (Af — Equatorial) — year-round warmth (27-30 degrees Celsius), heavy rainfall (3,000+ mm), no dry season. This diversity means India grows tropical fruits (mangoes, coconuts in Kerala), temperate fruits (apples, cherries in Kashmir), and subtropical crops (wheat in Punjab) — all within a single country.
Relevant Exams
World climate regions are a core geography topic for UPSC. Questions focus on the Köppen classification (group names and characteristics), climate-vegetation correspondence, Mediterranean climate features, India's climate zones, ENSO-monsoon linkages, and Thornthwaite system. SSC/RRB exams test factual recall — hottest/coldest places, desert locations, rainforest regions, wettest places, and basic climate zone definitions. Questions on climate change impacts (shifting biomes, IPCC projections), India's monsoon classification, teleconnections (El Nino, IOD), and climate extremes are increasingly asked across all exams.