Wind Formation, Types, and Global Wind Belts

Ocean Currents

• Ocean current: A large stream of moving water flowing through the ocean.
• Wind patterns create surface current patterns.

Causes of Wind

• Wind: The horizontal movement of air.
• Differences in air pressure create wind.
• Wind blows from high pressure to low pressure areas.
• Wind direction: Direction from which the wind is coming.
• Wind speed: Measured with an anemometer.
• Wind chill factor: Cooling effect caused by wind; the perceived decrease in air temperature.

Local and Global Winds

• Local winds blow over short distances, caused by unequal heating of the Earth's surface.
  • Sea breeze: Air above land heats faster than air above water (during the day); cool air blows inland.
  • Land breeze: Land cools faster than water (at night); cool air over land blows toward the water.
• Global winds blow steadily from specific directions over long distances.
• Temperature differences between the Equator and the poles cause convection currents.
• Coriolis effect: The curvature of wind due to the Earth's rotation.

Major Global Wind Belts

• Calm areas:
  • Doldrums: Occur near the Equator with little surface winds.
  • Horse latitudes: Subtropical regions with calm winds.
• Global wind belts:
  • Trade winds: Blow steadily toward the Equator (northeast in the Northern Hemisphere, southeast in the Southern Hemisphere).
  • Prevailing westerlies: Move from the west to the east in the middle latitudes.
  • Polar easterlies: Blow from high pressure areas near the poles toward low pressure areas within the westerlies.
• Jet streams: Long, narrow bands of strong wind in the upper atmosphere, usually blowing from west to east.