What is rain?

Rain is a natural precipitation phenomenon, which is caused by the disturbance of atmospheric circulation. It is an indispensable part of the earth's water cycle and the only way for almost all terrestrial plants far away from rivers to replenish fresh water. Raindrops fall from the sky, big and small, fast and slow. The water on the earth's surface evaporates and rises, and it cools to form rain. Rainwater is the most important fresh water resource in human life.

The water drops falling from the clouds and the water on the land and sea surface evaporate into steam. When the steam rises to a certain height, it becomes small water drops when it is cold. These small water droplets form a cloud, where they collide with each other and merge into large water droplets. When it is too big for the air, it will fall from the clouds and form rain. Rain is the most important fresh water resource in human life, and plants thrive on the moisture of rain and dew. But the flood caused by rainstorm will also bring great disaster to mankind.

Extended data

According to different standards, rainwater can be divided into the following categories:

1. According to the causes of precipitation, it can be divided into frontal rain (plum rain), convective rain, topographic precipitation and typhoon rain (cyclone rain).

2. According to the amount of precipitation, it can be divided into light rain, moderate rain, heavy rain, heavy rain and torrential rain.

3. According to the form of precipitation, it can be divided into snowfall, rainfall and hail.

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