Global & Local Winds
Wind Wind is created by differences in air pressure. The greater the pressure the faster the wind moves. Equator: warmer less dense air rises and creates an area of high pressure. Poles: colder, more dense air sink & creates areas of high pressure. Air moves from high to low pressure (poles to the equator)
How does the Sun’s energy produce wind? The unequal heating of Earth by the sun causes differences in air pressure. This causes convection currents, which produce wind.
Pressure Belts Equator: warm air rises & moves away & begins to cool, at 30 degrees N & S latitude are high pressure belts. Poles: cold air sinks & moves away & begins to warm, creating a low pressure belt around 60 degrees N & S latitude. Convection Cells: circular patterns caused by the rising & sinking of air. Coriolis Effect: the curving of moving objects, such as wind, by the Earth’s rotation. N. Hem. curves right S. Hem curves left
Two Types of Wind Local Winds: move short distances & can blow from any direction. Global Winds: are part of a pattern of air circulation that moves across the Earth (travel longer distances). Global winds include: trade winds, westerlies, & polar easterlies.
More about the types of WIND! Trade winds: blows from 30 degrees latitude to the equator. They meet in an area of low pressure around the equator called the doldrums (little wind b/c of warm rising air). About 30 degrees N and S. latitude, high pressure (horse latitudes) winds are weak.
Westerlies & Easterlies Westerlies: found between 30 degrees & 60 degrees latitude. They flow toward the poles in opposite direction of the trade winds. Polar Easterlies: cold, sinking air wind belts that extend from the poles to 60 degrees N & S latitude.
Jet Streams Jet streams are narrow belts of high speed winds that blow in the upper troposphere and lower stratosphere. They help meteorologists (track storms) and pilots (save time & fuel). Local winds are influenced by the geography of an area. sea and land breezes and mountain and valley breezes.