|MadSci Network: Environment/Ecology|
Why does it rain in the Rainforest?
It rains in the rain forest for two reasons. One is the same reason it rains where you live. Hot moist air hits colder air which causes the amount of moisture that the air can hold to decrease. Cold causes the molecules in the air to slow down, and when things slow down they tend to stick together more. Think about whipping cream, before you start to whip it it is liquid, and falls off the beaters, but as you whip it it becomes thicker and sticks to the beaters when you pull them out. So as air cools, the water in the air begins together and when enough of the water sticks together gravity pulls it to the earth and we call that rain.
The other reason that it rains in the rain forest is that the air can only hold so much water. This is called 100% humidity, that is the maximum amount of water air can hold. If water continues to evaporate because it is hot and the sun is shining then as much water evaporate will fall down as rain. It is the stickiness prinicipal again. When you have a room full of people everyone bumps into each other. Think of 100% humidity as a room that can't hold a single more person. If four more people come in, then four get pushed out. THat is why it can rain in the rain forest on a clear day, the air is already full of water and water continues to evaporate, and so some of it has to fall down as rain to make room for the water coming up.
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