4.5 Global Wind Patterns

Air Properties

• Warm air rises and holds more moisture than cold air.

• Rising air expands and cools, causing cool air to condense moisture into rain.

• After cooling and expanding, air sinks.

Coriolis Effect: Deflection of objects in the atmosphere due to Earth's spin.

• Air at 30° moves back to low pressure at the equator.

• Winds between 0°-30° move from East to West (Earth spins West to East).

• Winds between 30°-60° move from 30° to 60°, as Earth spins faster at 30° than at 60°.

Global Wind Patterns

• Air moves from 30° to 0° and 60° due to high pressure at 30° and low pressure at 0° and 60°.

• Rising air at the equator creates low pressure; sinking air at 30° is high pressure.

• Winds at 0° - 30° blow E→W (Eastern trade), influencing ocean currents clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere.

• Winds at 30° - 60° blow W→E (Westerlies), driving weather patterns in North America.

Pressure Summary

• 60° = Low Pressure

• 30° = High Pressure

• 0° = Low Pressure