World Climate Types (Köppen Classification): Equatorial, Monsoon, Savanna, Desert, Mediterranean, Temperate and Polar Climates

At a Glance

• Groups A tropical, B dry, C warm temperate, D cold, E polar
• Proposed by Wladimir Köppen, 1900
• Basis Temperature and precipitation
• Rainforest code Af
• Mediterranean code Cs
• Exam link UPSC Prelims, Geography: Climatology

Where Does It Fit?

This topic closes the macro on climatology by showing how the weather elements studied before combine into the climates of the world. The classification is used again in the macros on the physical geography of India and world regions. Previous topic: Indian Ocean Dipole Exception year…">Influence of El Niño/La Niña on the Indian Monsoon. Next topic: The Hydrological Cycle: Components and Processes.

What Is the Köppen Scheme and Why Is It Used?

In short: Köppen classified climates by temperature and rainfall because plants respond to those two things.

Wladimir Köppen was a climatologist and a botanist who noticed that natural vegetation is the best expression of the climate of a place. He therefore chose the temperature and rainfall limits that match the boundaries of vegetation zones, and he first presented the scheme in 1900, then revised it in 1918 and 1936, and later with Rudolf Geiger. The scheme is empirical: it uses only the monthly average temperature and precipitation, which are easy to measure, so it can be applied to any station. It has been updated with modern data, and remains the standard way to describe world climates. Other schemes give more weight to causes, such as the system of Thornthwaite, which uses the balance of precipitation and evaporation, or the system of Trewartha, who modified the Köppen scheme to reduce the size of the humid temperate group.

What Are the Five Groups and Their Criteria?

The groups A, C, D and E are set by temperature, and B by moisture. The tropical, warm temperate and cold groups are all humid.

What Do the Letter Codes Mean?

Each group is divided with small letters, usually the second letter for the precipitation pattern and the third for the temperature.

• Precipitation: f means no dry season; m means monsoon, with a short dry season; w means dry winter; s means dry summer; W means desert; S means steppe or semi-arid.
• Temperature: h means hot (annual mean above 18 degrees in the dry group); k means cold (below 18 degrees); a means hot summer (warmest month above 22 degrees); b means warm summer; c means cool and short summer; d means very cold winter; T means tundra and F means ice cap.
• Examples: Af is tropical rainforest; Am tropical monsoon; Aw tropical savanna; BWh hot desert; BSk cold steppe; Cfb marine west coast; Cs Mediterranean; Cwa humid subtropical; Df humid continental or taiga; ET tundra; EF ice cap.

Which Köppen Types Are Found in India?

The Indian types follow the monsoon, as in Monsoon Mechanism: Traditional and Contemporary Theories (Air Mass Theory, Jet Stream Theory). The scheme shows how little of India is truly temperate in the strict sense, since most of the country has a hot climate, with the temperate and cold climates found in the mountains.

What Is the Tropical Humid Climate?

In short: Group A is hot all year, with the rainfall controlled by the Intertropical Convergence Zone.

The tropical humid climates are found within about 15 to 25 degrees of the equator. The Sun is high throughout the year, so that every month has an average temperature of at least 18 degrees Celsius, and the annual range is small. The rainfall depends on the movement of the Intertropical Convergence Zone, ITCZ, the belt of rising air where the trade winds meet, which swings north and south with the Sun, as in General Circulation of the Atmosphere: Hadley Cell, Ferrel Cell, Polar Cell. Near the equator it is overhead nearly all year; farther away it brings a wet season and a dry season. The group has three types.

What Are the Features of the Tropical Rainforest Climate?

• Weather: hot, humid and the same every day: the daily range of temperature, about 8 to 10 degrees, is larger than the annual range. Rain falls in the afternoon from convectional clouds, often with thunder, as in Types of Precipitation: Convectional, Orographic, Cyclonic, Frontal, Monsoonal.
• Vegetation: tall evergreen trees in layers, with a canopy that blocks sunlight, a thin understorey, lianas and epiphytes. The Amazon forests are called selvas. It has the highest biodiversity of any biome.
• Soils: heavy rain leaches nutrients, making acidic, red laterite soils that are poor in humus, as in regur) Acidic leached soil Laterite Desert soil Arid soil, sandy Classification…">Types, Textures and Distribution of Soils in India. The fertility is in the living biomass, so that when the forest is cleared, farming fails in a few years, which is why shifting cultivation is common.
• People: sparse populations such as the Pygmies of the Congo and the tribes of the Amazon, with plantation crops such as rubber, oil palm, cocoa and bananas.
• Threats: deforestation for cattle, soya, palm oil and mining, which reduces the rainfall that the forest itself recycles. Scientists warn that parts of the Amazon may approach a tipping point to savanna if clearing and warming continue.

What Are the Monsoon and Savanna Climates?

The tropical monsoon climate is created by the seasonal reversal of winds. In summer, moist winds from the ocean bring torrential rain, and in winter, dry land winds bring a short dry season. In India it is found along the Malabar coast and in the Western Ghats, with evergreen and semi-evergreen forests. The monsoon system is explained in Monsoon Mechanism: Traditional and Contemporary Theories (Air Mass Theory, Jet Stream Theory). It has dense populations, because of the combination of heat and plentiful water: South Asia and Southeast Asia grow rice, jute, tea, sugarcane and spices.

The tropical savanna climate lies on the poleward side of the rainforest, where the ITCZ brings rain only in summer and the subtropical high brings drought in winter. The grass grows tall in the wet season, and turns brown and often burns in the dry season. Fire, grazing and drought keep trees scattered. The African savanna supports the largest herds of grazing animals, such as zebra, wildebeest and elephants, and predators such as lions. People herd cattle, as the Masai do, and grow millet, sorghum, cotton and groundnut. Savannas are under pressure from overgrazing, farming and drought, which drive desertification at their dry edges.

As an analytical point, the three climates form a gradient controlled by one thing, the length of the dry season, and since the ITCZ is shifting in a warming world, the boundaries between them may move.

What Are the Dry Climates of Group B?

In short: dry climates are not defined by a low temperature, but by evaporation exceeding rainfall.

Group B covers about a quarter to a third of the land surface, and is divided into the desert, with the letter W, and the steppe, with the letter S; the second letters h and k stand for hot and cold. There are four main types.

Aridity has four causes. The first is the subtropical high pressure belt at about 15 to 30 degrees, where air sinks and warms, which explains the Sahara, Arabia and the Thar, as in General Circulation of the Atmosphere: Hadley Cell, Ferrel Cell, Polar Cell. The second is the rain shadow of mountains, which explains Patagonia and the Great Basin, as in Types of Precipitation: Convectional, Orographic, Cyclonic, Frontal, Monsoonal. The third is a cold ocean current along a western coast, which cools the air and prevents rain, as in the Atacama and the Namib, as in Major Ocean Currents of the World and Their Effects. The fourth is distance from the sea, which explains the Gobi and Turkestan. Deserts have a huge daily range of temperature, and the occasional rain causes flash floods. Oases, exotic rivers like the Nile and mineral wealth such as oil in Arabia support settlements, while nomadic herding is the main way of life.

What Are the Warm Temperate Climates of Group C?

The climate of the Mediterranean is a special case, since it is the only climate in which rain falls in winter and the summer is dry, because the zone of winds shifts with the Sun, as in General Circulation of the Atmosphere: Hadley Cell, Ferrel Cell, Polar Cell. This is why the Mediterranean regions are called the orchards of the world. The humid subtropical climate is sometimes called the China type, and the marine climate the British type.

What Are the Cold Snow-Forest Climates of Group D?

In short: Group D climates have the most extreme annual range of temperature on Earth, with long, bitter winters and short, warm summers.

Group D is found only in the northern hemisphere, in the interiors and the eastern parts of the great land masses of North America and Eurasia between about 40 and 70 degrees north. There is no Group D in the southern hemisphere, because there is no land mass at those latitudes that is large and far enough from the sea. The distance from the sea produces continentality, with a very large annual range of temperature, as in Factors Controlling the Distribution of Temperature. The rainfall is moderate, about 40 to 100 cm, mostly in summer from convection, with snow in winter, which comes from temperate cyclones, as in Temperate (Extra-Tropical) Cyclones: Air Masses, Fronts, Origin and Development.

The taiga, or boreal forest, is the largest forest biome of the world. The trees are mainly spruce, fir and pine, with needle-shaped leaves and conical shapes that shed snow and conserve water. The soil is a poor, acidic podzol. Verkhoyansk and Oymyakon in northeastern Siberia have a winter minimum near minus 68 degrees Celsius, the lowest temperature of a permanently inhabited place, but a summer that can pass 30 degrees, giving an annual range of well over 60 degrees. In India, the Dfc type is found in a small part of Arunachal Pradesh.

What Are the Polar Climates of Group E?

• Tundra (ET): the warmest month is between 0 and 10 degrees Celsius. It lies along the Arctic coasts of North America and Eurasia and on the fringes of Antarctica and high mountains. The ground is frozen as permafrost, and only the thin surface layer thaws in summer, forming marshes. The vegetation includes mosses, lichens, sedges and dwarf shrubs, and no trees. The Inuit, Sami and Nenets have traditionally hunted and herded reindeer.
• Ice cap (EF): every month is below 0 degrees Celsius, and ice covers the land permanently, as in Greenland and Antarctica. Antarctica is the coldest, driest and windiest continent, with the lowest recorded temperature of about minus 89 degrees Celsius at Vostok, and it holds around 90 per cent of the world’s ice.
• Light and dark: near the poles, the Sun does not set for weeks to months in summer, called the midnight sun, and does not rise in winter, called the polar night. The Sun is always low, and the ice reflects most of the light, which is why the poles are cold, as in Heat Balance of the Atmosphere: Conduction, Convection, Advection, Terrestrial Radiation, Albedo.
• Highland climate (H): the Himalaya and other high mountains have a polar-type climate at the top, with the climate changing with altitude, and the snow line on the Himalaya is at around 4,500 to 5,500 metres.

Why Is This Topic Important?

• Core topic Basis of world climates
• Application Indian climate types
• Climate change Shifting zones

What Came Next?

The next macro covers oceanography, beginning with the hydrological cycle. Next topic: The Hydrological Cycle: Components and Processes.

Key People and Terms

• Köppen scheme Empirical climate classification
• Group A Tropical humid
• Group B Dry
• Group E Polar
• Thornthwaite Alternative scheme based on moisture balance
• Highland climate Altitude-controlled climate

Exam Corner

Mains Angle

Questions ask to apply the scheme to India. These points add depth.

• Basis Vegetation-linked limits
• India Mostly A and B with Cwg
• Limit Averages and static zones