Earth’s Atmosphere Global Atmospheric Circulation

Wind Wind is caused by differences in atmospheric pressure from place to place. Air tends to move from high to low pressure until the air pressures are equal. For example, pressure was higher over Wichita than Columbus, a pressure gradient force would push air from Wichita to Columbus. Isobars and a pressure gradient. High pressure is centered at Wichita, and low pressure is centered at Columbus.

Pressure Gradient and Winds

The Coriolis Effect An object in motion on the Earth's surface always appears to be deflected away from its course. This effect is a result of the Earth's rotation, and is called the Coriolis effect. Coriolis effect direction and strength. The Coriolis effect acts to deflect the paths of winds or ocean currents to the right in the northern hemisphere and to the left in the southern hemisphere as viewed from the starting point. Click me Visualization…

Wind Terminology Wind Direction: direction from which the wind blows Prevailing Winds: direction from which winds tend to blow at a given location Windward: facing the direction from which the wind blows Leeward: facing the direction in which the wind is blowing

Subglobal Wind Systems Land breeze-Sea breeze Mountain breeze-Valley breeze Drainage (katabatic) winds Chinook-type winds Monsoons

Land Breeze-Sea Breeze

Mountain Breeze-Valley Breeze/ Drainage Winds (e.g. Bora, Mistral)

Chinook, Foehn, Santa Ana, Winds

Monsoon Winds

Global Pressure Belts Surface Winds on an Ideal Earth A parcel of air in motion near the surface is subjected to three influences: the pressure gradient that propels the parcel toward low pressure; the Coriolis effect that deflects the parcel, and the frictional forces of the ground surface that slow the parcel down. Surface Winds on an Ideal Earth

Global Atmospheric Circulation

Surface Winds on an Ideal Earth Global surface winds on an ideal Earth. This schematic diagram of global surface winds and pressures shows the features of an ideal Earth, without the disrupting effect of oceans and continents and the variation of the seasons. Surface winds are shown on the disk of the Earth, while the cross section at the right shows winds aloft.

Jet Streams: extremely strong upper-air currents Jet Stream Analyses and Forecasts ‘Inside the Jet Stream’

Rossby Waves