If the rate of fall is more than 0, the rain will go up. If the rate of fall is less than 0 or 0, the rain will go down. If the rate of fall is more than 0, the more up you put the faster it goes up. If the rate of fall is less than 0 or 0, the more down you put it (such as -20 to -21 or -10 to -12), the faster it goes down.
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