Koeppen's classification of world climates

Tundra regions remain very cold for most of the year, and the brief summer provides only a short growing season. Frozen ground or permafrost can also restrict deep root development and drainage. These conditions allow mosses, lichens, grasses, and low shrubs, but usually not tall trees. Extreme heat, industry, and trade are not the general climatic reasons for the lack of trees. Hence B is correct.

Ice-cap climate is the Köppen EF type. Even the warmest month has an average temperature below 0°C, so snow and ice persist and the land remains ice-covered for most or all of the year. Grasslands and crops require a substantially warmer growing season, while sand is not the defining surface cover. Therefore, land covered with ice is the correct description.

Köppen classification communicates climate groups and their subtypes through letter symbols. The first capital letter identifies the major group, while additional lowercase letters describe rainfall seasonality or temperature characteristics. Colours may be used on maps to display the symbols, but they are not the basic classification code. River numbers, population signs, and flags are unrelated, so letter symbols are correct.

Tropical monsoon climate, commonly represented by Am, receives much of its rainfall during the summer monsoon season. Seasonal heating creates lower pressure over land, draws moist winds from the ocean, and produces heavy rain. The winter season is often comparatively drier, although local patterns vary. The options referring to spring or autumn do not express the characteristic dominant rainy season, so A is correct.

Savanna climate has a marked wet season and a distinct dry season. This seasonal water supply favours tall grasses along with scattered trees that can tolerate periodic drought, such as acacia in many regions. Dense evergreen rainforest requires more continuous moisture, coniferous forests are associated with cooler climates, and mosses and lichens are typical of tundra. Thus A is correct.

Desert climate is defined by extreme aridity, so annual precipitation is very low and often irregular. The important feature is not simply that rain is absent, but that moisture input is insufficient compared with atmospheric water demand. Uniformly high rainfall is characteristic of humid climates, while snowfall may occur in some cold deserts but is not the general defining feature. Therefore, very low rainfall is correct.

Steppe climate is semi-arid, so it receives more precipitation than a true desert, although the moisture is still insufficient for dense natural forests. Its grasslands are therefore more extensive than desert vegetation. Steppe regions are not always colder, because they may be hot or cold depending on location and season. They are also not identical to deserts and are not snowy throughout the year. Hence A is correct.

Mediterranean climate has hot, dry summers and mild, wetter winters. In winter, the shifting belt of westerlies and associated temperate cyclones commonly brings rainfall to these regions. Summer is dry because subtropical high pressure suppresses cloud formation. Rainfall is therefore not usually equal throughout the year, and the climate is not defined by a summer maximum. Winter is the correct answer.

Marine west coast climates are strongly influenced by the nearby ocean. Water heats and cools more slowly than land, so it reduces both summer heat and winter cold. Cloud cover and prevailing westerlies may also moderate conditions. Consequently, temperatures are generally mild or moderate and the annual range is relatively small. Extreme temperatures, permanent freezing, and desert heat are not defining features, so B is correct.

The lowercase f in a Köppen symbol means that there is no distinct dry season; precipitation remains sufficiently distributed through the year according to the relevant climate criteria. It does not mean that every day is rainy or that every month receives exactly the same amount. A dry summer is represented by s and a dry winter by w. Therefore, the absence of a clear dry season makes A correct.

In Köppen notation, the lowercase s indicates a dry summer. This is characteristic of Mediterranean-type climates, where subtropical high pressure suppresses summer rainfall and winter disturbances bring more moisture. The lowercase w indicates a dry winter, while f indicates no distinct dry season. Thus s should be remembered as summer dryness, making option B unambiguous.

The lowercase w in Köppen classification indicates a dry winter. In such climates, rainfall is relatively greater during the warmer part of the year, while winter has a pronounced rainfall minimum. The lowercase s has the opposite meaning, namely a dry summer, and f means no distinct dry season. Therefore, the season identified by w is winter, so B is correct.

Capital D denotes the cold snow-forest or continental climate group in Köppen’s system. These climates generally have cold winters and a larger annual temperature range than maritime climates; coniferous or mixed forests may occur where moisture is sufficient. Tropical rainforest is Af, hot desert is commonly BWh, and ice-cap climate is EF. Therefore, the cold snow-forest climate is the correct choice.

Af is the tropical rainforest climate in Köppen’s system. High temperatures throughout the year, abundant precipitation, and the absence of a pronounced dry season support dense, tall, multilayered evergreen forests. Thorny shrubs and cacti are associated with dry climates, whereas mosses and lichens are typical of tundra. Therefore, dense evergreen forest is the most appropriate vegetation for Af climate.

BWh denotes a hot desert climate: B means dry, W identifies a desert subtype, and h indicates a hot thermal condition. The Sahara has extremely low and irregular rainfall along with high temperatures, making it a classic BWh example. The Amazon Basin is mainly Af, Greenland’s ice-covered areas are associated with EF, and cold Siberian forest regions belong to colder D climates. Hence A is correct.

The Amazon Basin lies largely near the Equator and has persistently high temperatures, abundant rainfall, and no pronounced dry season over most of its area. These conditions correspond to Af, the tropical rainforest climate. Am is tropical monsoon climate and may include a short dry period; BS is semi-arid steppe climate, and ET is tundra climate. Therefore, Af is the best general classification for the Amazon Basin.

In Köppen’s classification, Am denotes a tropical monsoon climate. It combines persistently high temperatures with a pronounced seasonal rainfall pattern, in which the monsoon supplies most of the annual precipitation. This makes Am useful for identifying humid monsoon-influenced regions. EF is ice-cap climate, BWk is cold desert, and Cfb is temperate oceanic climate, so none of them expresses the tropical monsoon condition as directly as Am.

Greenland’s interior is covered by a vast permanent ice sheet, and the mean temperature of its warmest month generally remains below 0°C. Köppen’s EF symbol represents ice-cap climate under this condition. ET, or tundra climate, requires the warmest month to average above 0°C but below 10°C and is more typical of ice-free margins. Cs and BS represent Mediterranean and steppe climates, not the ice-covered interior.

A Köppen code is read from the broad climate group to its more specific characteristics. The first capital letter identifies the main group, such as A for tropical, B for dry, C or D for temperate and continental conditions, and E for polar climates. Smaller letters then describe rainfall seasonality or temperature features. The other options concern unrelated geographical or social information and cannot explain a climate symbol.

Group B in Köppen’s system is the dry-climate group. Within it, BW denotes desert climates, where moisture deficiency is especially severe, and BS denotes steppe or semi-arid climates, which are somewhat less dry. Group A contains tropical climates, Group C contains warm temperate climates, and Group E contains polar climates. Therefore, only Group B includes both the desert and steppe categories.

Af is the Köppen symbol for tropical rainforest climate. It occurs in regions with persistently high temperatures and no pronounced dry month; every month receives meaningful rainfall. BW represents desert and BS represents steppe climate, both of which are moisture-deficient. EF represents ice-cap climate, where temperatures are extremely low. Thus Af best matches the combination of year-round heat and abundant rainfall.

EF denotes Köppen’s ice-cap climate. Its defining condition is that even the mean temperature of the warmest month remains at or below 0°C, allowing snow and ice to persist throughout the year. Cfb is a mild oceanic climate, Am is tropical monsoon climate, and BSh is hot semi-arid climate. Those climates may have cool or dry seasons, but they do not support permanent ice in the way EF does.

A Köppen climate map normally uses colours to separate broad or regional climate zones, while letter symbols identify the exact classification and its important characteristics. For example, Af, BW or EF conveys more specific information than colour alone. Country flags, city counts and mineral signs are not part of the climate-code interpretation. Therefore, the map legend and its letter symbols should always be read with the colours.

In Köppen’s classification, the capital letter E identifies polar climates. ET is tundra climate: the warmest month averages above 0°C but below 10°C. EF is ice-cap climate: even the warmest month remains at or below 0°C. Af and Am are tropical, BW and BS are dry, and Cs and Cf are temperate categories. Thus ET and EF are the only pair made entirely of polar symbols.

Köppen Group B contains dry climates. BW is the symbol for desert climate, while BS represents steppe or semi-arid climate, so both symbols in option A are dry types. Af and Aw belong to the tropical group, ET and EF to the polar group, and Cf and Df to humid temperate or continental categories. Therefore, BW and BS are the only pair consisting entirely of dry-climate symbols.