When warm, moist air sweeps in from the ocean and rises over a mountain range,
it expands and cools. Explain how this cooling is related to the attractive
forces between gas molecules. Why does this cause rain to form? When the air
drops down the far side of the range, its pressure rises as it is compressed.
Explain why this causes the air temperature to rise. How does the humidity of
this air compare with the air that originally came in off the ocean? Now
explain why the coast of California is lush farmland, whereas valleys (such as
Death Valley) that lie to the east of the tall Sierra Nevada mountains are
arid and dry.