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Geography

Tropical rainforests

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The tropical rainforest is a unique biome [biome: A large-scale ecosystem that can be categorised into one of ten different types. The type of biome is defined mainly by its climate. ] with a constant temperature and a high rainfall. The level of humidity [humidity: Humidity is the amount of water vapour in the atmosphere. Air can only hold a certain amount of water before condensation and precipitation occurs. Humidity is measured as a percentage, relative to the saturation point where the air can hold no more water vapour (i.e. 100 percent humidity). ] and denseness of the vegetation give the ecosystem a unique water and nutrient cycle. Rainforests around the world are threatened by the expansion of man.

The tropical rainforest

A tropical [tropical: the area between the Tropic of Cancer and the Tropic of Capricorn - two imaginary lines 23.5 degrees of latitude to the north and south of the equator; anything coming from that region. ] rainforest is a type of biome [biome: A large-scale ecosystem that can be categorised into one of ten different types. The type of biome is defined mainly by its climate. ] found in hot, humid environments in equatorial climates. They contain the most diverse range and highest volume of plant and animal life found anywhere on earth.

map showing the distribution of savannah across the world

Distribution of savannah across the world

In general, tropical rainforests have hot and humid climates, where it rains virtually everyday. At some parts of the year the rainfall is extremely heavy, while in other parts of the year it will rain a lot less. Temperatures vary through the year - but much less than the rainfall.

The graphic shows average rainfall and temperature in Manaus, Brazil, in the Amazon rainforest. Total rainfall is 2104mm per year, most of it during the rainy season from December to May. Notice how much the rainfall varies over the year: the highest monthly rainfall is in March with over 300mm, while the lowest is in November with less than 50mm. Meanwhile the temperature only varies by 2°C.

chart showing the annual rainfall and annual temperature of Manaus, Brazil

Average monthly rainfall and temperature in the rainforest area of Manaus, Brazil.

Compare this pattern of rainfall and temperature with the one for savannah grassland. Make sure you know the differences between them!

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