Mountains:
There are two sides: wayward and leeward.
Wayward: Whenever it is raining, the wayward side gets the
rain so there is good soil most of the time. But as the cloud goes up the
mountain, it keeps raining until soon there is no more water in the cloud.
Leeward:
Now the cloud is at the other side of the mountain. There is no more
precipitation so the leeward side of the mountain gets no rain so the flat
ground on this side of the mountain is dry and humid.