World Climate Types & Climatic Regions – NDA Geography Notes

Weather is what happens in the atmosphere on a given day. Climate is the average pattern of weather over many years, typically 30 or more. While weather is unpredictable, climate is remarkably consistent. The tropical rainforest is always hot and wet. The Sahara is always hot and dry. The Arctic is always cold. These patterns are not accidents. They result from latitude, pressure belts, wind patterns, ocean currents, and continental position working together.

NDA tests this chapter through climate type identification from given characteristics, matching climate types with regions or cities, and specific questions about Mediterranean climate, monsoon, and tundra. Understanding the logic of why each climate exists where it does is the key to answering unfamiliar questions.

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The Basis of Climate Classification

Six interacting factors determine climate:

Latitude: determines solar energy received; the most fundamental factor. Altitude: higher areas are cooler (6.4°C per km). Distance from ocean: oceans moderate temperature; continental interiors have extreme ranges. Prevailing winds: determine moisture or dryness. Ocean currents: warm currents raise coastal temperatures; cold currents cool and suppress rainfall. Topography: mountains create rain shadows.

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Equatorial Climate

Location: Within 5°–10° of the equator: Amazon Basin (South America), Congo Basin (Africa), and islands of Southeast Asia.

Temperature: High throughout the year: average 26–28°C. No real seasons. Rainfall: Heavy throughout the year: annual rainfall exceeds 2,000 mm. Convectional rainfall almost every afternoon.

Key features: No dry season | highest biodiversity on Earth | dense tropical rainforest (selvas) | very small annual temperature range.

The equatorial regions experience more than one period of rainfall maximum in a year: double rainfall maxima around the equinoxes (March and September) when the ITCZ passes overhead twice as it migrates north and south.

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Tropical Monsoon Climate

Location: South Asia (India, Bangladesh, Myanmar), Southeast Asia, West Africa.

Temperature: Hot throughout the year: with a very hot dry season and a cooler wet season. Rainfall: Strongly seasonal: most rainfall in 3–4 monsoon months; dry for the rest. Total annual rainfall can be very high (Cherrapunji, India: over 11,000 mm per year).

Key features: Strongly seasonal rainfall | distinct wet and dry seasons | driven by seasonal reversal of winds.

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Tropical Savanna Climate

Location: Between the equatorial zone and tropical deserts, approximately 5°–20° latitude in Africa, South America, and northern Australia.

Temperature: Hot throughout the year. Rainfall: Seasonal: a distinct wet season (ITCZ moves over the region) and a distinct dry season (subtropical high pressure belt dominates). Annual rainfall typically 600–1,500 mm.

Key features: Tall grasses with scattered trees (acacia in Africa) | fires common in the dry season | lies between equatorial zone and hot deserts.

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Mediterranean Climate: Special Focus

Location: Found on the western sides of continents between approximately 30° and 45° latitude: the Mediterranean basin, California (USA), central Chile, southwestern Australia, and the Cape of Good Hope (South Africa). [NDA 2010-II]

Temperature: Hot, dry summers. Mild, wet winters. Rainfall: Comes in winter: 300–900 mm annually, mostly October–March (Northern Hemisphere). Summers are dry.

Why winter rainfall? In summer, the subtropical high pressure belt sits over these regions, suppressing rainfall. In winter, this belt moves equatorward and the westerlies bring frontal rain. Summer drought, winter rain: the reverse of most tropical climates.

★ IMPORTANT Mediterranean climate is one of the most frequently tested climate types in NDA. Four defining characteristics: (1) Hot dry summer. (2) Mild wet winter. (3) Western coasts of continents between 30° and 45° latitude. (4) Annual rainfall 300–900 mm with winter maximum. [NDA 2006-I | NDA 2010-II]

City examples:

Region	Mediterranean Cities
Mediterranean basin	Rome, Athens, Lisbon, Barcelona
California, USA	Los Angeles, San Francisco
Central Chile	Santiago
South Africa	Cape Town
Southwestern Australia	Perth, Adelaide

NOT Mediterranean: Buenos Aires (humid subtropical) | Tokyo (humid subtropical) | Kolkata (monsoon) | eastern coast cities in general.

Mediterranean agriculture: Grapes, olives, citrus fruits, and wine: all adapted to the hot dry summer and mild wet winter.

Vegetation: Sclerophyll shrubs (hard, waxy leaves adapted to drought): maquis (France), chaparral (California), fynbos (South Africa), mallee (Australia).

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Hot Desert Climate

Location: Subtropical high pressure belts: approximately 20°–30° latitude. The Sahara, Arabian Desert, Thar Desert, Australian Desert, Atacama, and Kalahari.

Temperature: Very high in summer (exceeding 50°C); cold at night and in winter because lack of cloud cover allows rapid heat loss. Rainfall: Extremely low: less than 250 mm per year.

Key features: Greatest daily temperature range | almost no clouds | very low humidity | xerophytic vegetation.

Hot deserts are in the subtropical high pressure belt because sinking air suppresses cloud formation and rainfall.

The world’s driest place is the Atacama Desert in Chile. The lowest temperature on Earth was recorded at Vostok Station, Antarctica at −89.2°C.

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Steppe Climate

Location: Continental interiors in mid-latitudes: the steppes of Central Asia and Russia, the Great Plains of North America.

Temperature: Large annual range: hot summers, cold winters. Rainfall: Low: 250–500 mm per year. Too dry for forests but enough for grasses.

Key features: Temperate grasslands | very large seasonal temperature range | fertile soils (chernozem) | NOT year-round rainfall. [NDA 2006-I]

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Temperate Oceanic Climate

Location: Western coasts of continents between about 40°–60° latitude: Western Europe (UK, France, Germany, Netherlands), Pacific coast of North America, southern Chile.

Temperature: Moderate: neither very hot in summer nor very cold in winter. Rainfall: Moderate to heavy throughout the year, slight winter maximum.

Key features: Mild, wet climate | no extreme temperatures | deciduous forests.

Western Europe has a mild, wet climate because of the North Atlantic Drift (extension of the Gulf Stream) which warms the western coasts, keeping them much milder than places at similar latitudes elsewhere. [NDA 2010-I]

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Temperate Continental Climate

Location: Deep continental interiors of North America and Asia.

Temperature: Extreme: very hot summers, very cold winters. The largest temperature ranges of any climate type. Rainfall: Low: 250–500 mm: mainly in summer.

Key features: Greatest annual temperature range | short hot summer; very long bitterly cold winter | grasslands and prairies.

The Verkhoyansk area of Siberia, Russia, sometimes called the pole of cold: has the greatest temperature range of any inhabited place on Earth (below −70°C in winter; above 30°C in summer).

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Taiga and Tundra Climates

Taiga (Sub-Arctic Climate)

Location: Large band across Canada, Alaska, Russia, and Scandinavia, roughly 50°–70°N. Temperature: Short cool summers; extremely cold long winters. Rainfall: Very low (200–500 mm), mostly snow.

Key features: Dominated by coniferous forest (boreal forest) | very short growing season (<4 months) | permafrost in some areas.

Tundra Climate

Location: Above the Arctic Circle, northern Canada, Alaska, Siberia, and Greenland. Also found at high altitude in mountains (alpine tundra). Temperature: Always cold: average temperature of the warmest month is below 10°C. Rainfall: Very low (<250 mm), mostly snow.

Key features: No trees | vegetation = mosses, lichens, sedges, dwarf willows | very short growing season (<2 months) | permafrost.

The absence of trees in the tundra is due to permafrost, permanently frozen subsoil that prevents tree roots from penetrating. Cold temperature alone is not the primary reason. [NDA 2011-I]

Taiga vs Tundra: Taiga = coniferous forest (trees present; subarctic). Tundra = treeless (permafrost; polar). Taiga is warmer than tundra.

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Ice Cap Climate

Location: Greenland and Antarctica. Temperature: Always below freezing: average monthly temperatures never rise above 0°C. Rainfall: Virtually zero.

Key features: Permanent ice cover | no vegetation | world’s lowest recorded temperatures (Vostok Station, Antarctica: −89.2°C).

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Mediterranean vs Monsoon: Key Distinction

NDA has directly tested the difference between Mediterranean and monsoon climates.

Feature	Mediterranean	Monsoon
Rain season	Winter	Summer
Dry season	Summer	Winter
Location	West coast, 30°–45°	South/Southeast Asia, West Africa
Cause of rain	Westerlies + frontal systems	ITCZ migration + sea-land pressure difference
Vegetation	Sclerophyll shrubs	Tropical deciduous/monsoon forest

Mediterranean = winter rainfall + summer drought. Monsoon = summer rainfall + winter drought. These are mirror images.

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Koppen’s Climate Classification

The most widely used climate classification system was devised by Wladimir Koppen: classified based primarily on temperature and precipitation patterns, related to natural vegetation.

Group	Label	Description
A	Tropical	No cold season; all months above 18°C
B	Dry	Evaporation exceeds precipitation
C	Temperate	Mild winters; coldest month 0°C to 18°C
D	Continental	Cold winters; coldest month below 0°C
E	Polar	No warm season; warmest month below 10°C

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Climate Sequence on Western Coasts

Moving from the equator poleward on the western side of a continent:

Equatorial (0°–10°) → Savanna (10°–20°) → Desert (20°–30°) → Mediterranean (30°–45°) → Temperate Oceanic (45°–60°) → Tundra (above 65°)

This sequence follows the pressure belt pattern: equatorial low, subtropical high (desert), then the westerlies zone (temperate oceanic), then polar (tundra).

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