4.5

Cold air

denser than warm air, sinks, creates high pressure, holds less moisture

Warm air

less dense than cold air, rises, creates low pressure, holds more moisture

Air column

rising air expands and cools, sinking air compresses and warms

Coriolis effect

deflection of air and water due to Earth’s rotation

Hadley cells

convection cells between equator and ~30° latitude, drive trade winds

Trade winds

winds blowing from east to west in the tropics, northeast in Northern Hemisphere, southeast in Southern Hemisphere

Ferrel cells

mid-latitude convection cells between ~30° and 60°, drive westerlies

Westerlies

winds blowing from west to east in mid-latitudes

Polar cells

convection cells near poles, drive polar easterlies

Polar easterlies

cold winds blowing from east to west near poles

Global wind patterns

result from solar heating at equator and Coriolis effect, distribute heat and moisture around Earth