3.4 Factors Affecting Temperature & Precipitation

Equator Prime Meridian

Tropic of Cancer Equator Tropic of Capricorn North temperate zone Tropic zone Tropic of Capricorn South temperate zone

Hotter places means more evaporation of water to form clouds, which in turn leads to rain.

height above sea level As elevation increases, the air gets thinner, which means less air molecules and they move slowly, producing less energy.

Ocean water evaporates because it is being heated by the sun Ocean water evaporates because it is being heated by the sun. Warm air is less dense and so it rises. This warm air carries the moisture with it. As this warm air reaches high elevation, where it is cold, it sinks and condenses to produce rain. Now this “dried air” keeps moving and the other side of the mountain gets dry air (no rain) and gets a desert.

Look at where the deserts are compared to where the mountains are.

Do you think places along the coast are always milder in temperature Do you think places along the coast are always milder in temperature? And get more rain?

What do you think conditions are like at the Atacama Desert?

Atacama Desert Some areas haven’t had rain for 400 years. There is snow. But isn’t it on the coast? Shouldn’t it have mild weather?

The coast carries a cold current.

What if the ocean current is a cold one What if the ocean current is a cold one? Do we still get moist air above it? No, the air above the cold current is cold, little evaporation occurs.

densities temperature salinity wind rotation of the earth Generally warmer, milder winter Might be warm during the day depending on latitude/elevation, but cold nights Lots of warm moist air, lots of precipitation Lack of warm moist air, little precipitation