Why do air pressures vary? The unequal heating of Earth’s surface generates pressure differences Air Pressure Review

 Weather & Air Pressure • Low Pressure: Rising air associated with cloud formation and rain. High Pressure: Sinking air and clear skies  Weather Forecasting • Low-pressure centers can produce extreme weather any season.

Three factors combine to control wind: (Video) Pressure Differences, The Coriolis Effect, and Friction.

Isobars spaced close together show a steep pressure gradient Pressure Differences The greater the pressure gradient the gustier the wind Isobars spaced close together show a steep pressure gradient

How Earth’s rotation affects moving objects Coriolis Effect How Earth’s rotation affects moving objects

Coriolis Effect Winds in the Northern Hemisphere curve clockwise, and winds in the Southern Hemisphere curve counterclockwise -If you fire a cannonball from the equator to the North Pole, the cannonball continues to move in a straight path at the same speed -The Earth continues to rotate underneath

Friction Acts to slow air movement, which changes the wind’s direction Above the surface Faster Wind

Winds near the top of the troposphere, like jet streams, are not influenced by friction Jet streams are fast rivers of air that travel between 120 and 240 kilometers per hour in a west-to-east direction