Why is the rainforest so rainy?
Near the equator the sun is high all year, heating the ground and oceans so much that warm, moist air rises almost every afternoon into towering thunderstorms. The forest then breathes much of that water back into the air to rain again.
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Where the trade winds meet
The trade winds from the northern and southern hemispheres flow toward the equator and meet in a belt of rising air called the Intertropical Convergence Zone. Rising, moist air builds clouds and storms, so this belt is one of the rainiest places on Earth. It shifts north and south with the seasons, bringing wet and dry seasons to places at its edges.
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The forest makes its own weather
Trees pull water from the soil and release it through their leaves. Over the Amazon this happens on such a scale that a large share of the rain is recycled moisture the forest has put back into the air, carried west on the wind to fall again further inland. Cutting down large areas of forest can make the region drier.
Hot but rarely scorching
Rainforests are warm and humid all year, usually in the 80s °F by day, but rarely extremely hot: clouds and constant evaporation keep the heat in check. The muggy feeling comes from dew points in the 70s.
Questions people ask
- Why are there no seasons in the tropics?
- There are wet and dry seasons, but temperatures change little because the sun stays high in the sky all year.
- How much rain does a rainforest get?
- Typically more than 70 to 80 inches a year, and some places get several times that.