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信息发布者：
Weather comes from the earth's atmosphere and the sun's heat.
Air.
Hot air rises, leaving a space behind.Cooler air goes into that space.
The water vapour in clouds cools and becomes raindrops.The raindrops get bigger and heavier 
until they fall from the cloud.
If the temperature is below freezing,tiny bits of ice called crystals form in a cloud.When ice crystals 
fall and stick together,they become snowflakes.
D


B

D
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