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Wind. Wind is the general horizontal motion of air from one location to another based on differences in air pressure Air speed is measured by an anemometer Air movement is governed primarily by Pressure gradient force Coriolis force Friction force. What causes wind movement.
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Wind • Wind is the general horizontal motion of air from one location to another based on differences in air pressure • Air speed is measured by an anemometer • Air movement is governed primarily by • Pressure gradient force • Coriolis force • Friction force
What causes wind movement • Direction is governed by the path of least distance between high pressure and low pressure • Pressure gradient • Speed will increase if there is a larger difference between pressures • Steep pressure gradient
RESULTANT WIND • FUNCTION OF 3 THINGS • PGF + CF + FRICTION • PGF AND CF ARE AT ODDS • FRICTION DEFLECTS WINDS SLIGHTLY IN FAVOR OF PGF • WHAT HAPPENS IN THE UPPER ATMOSPHERE?
H L Pressure gradient
The Coriolis Effect • When wind moves from zones of high pressure to zones of low pressure it veers due to earth rotation • To the right in the northern hemisphere • To the left in the southern hemisphere • Equator faster rotation than the poles • Demo – • http://www.classzone.com/books/earth_science/terc/content/visualizations/es1904/es1904page01.cfm?chapter_no=visualization
Remembering the direction of bend in the coriolis effect Bends to the right Bends to the left
Effect of coriolis force • Strongest at higher latitudes • Weakest at the equator • The effect of coriolis increases with increasing windspeed • The combined effect of coriolis and pressure gradient force makes winds travel parallel to isobars = • Geostrophic Wind
Friction force • Effects of surface friction occur to ~ 5000 ft above the ground • Cause winds to slow down and generally move across isobars • More pronounced when wind speeds are higher