High Altitude Winds
PHYSICAL GEOGRAPHY 101

Geostrophic Winds

At low altitudes - winds move across isobars at an angle (Coriolis effect)
At high altitudes (7-14 km) winds flow parallel to the isobars.
Coriolis effect still influences the high altitude winds

Global Circulation at High Altitude

Similar to low altitude but with differences.
1) Equatorial Easterlies - 15°S-15°N Lat.
2) Tropical High-Pressure Belt - 15°-20° Lat.
3) Upper-air Westerlies - 25° Lat. to poles

Rossby Waves

Rossby waves are undulations which form in the Upper-air Westerlies. Also known as Longwaves.
They form along the Polar Front and are a means of equalizing temperatures between the cold and warm air masses that make up the Polar Front.
The waves move from west to east.
Shorter waves can be found within the longwaves.
Smaller waves move faster than longwaves.

Jet Streams

Narrow zones of high speed, high altitude air flow.
Three kinds of Jet Streams

Polar-Front Jet Stream

Occurs along the Polar Front
Associated with Rossby Waves
Found between 35°-65° Lat.
10-12 km altitude
Wind speeds of 350-450 kph
Winds flow west to east

Subtropical Jet Stream

Occurs just poleward of the Hadley Cell
Found at ~30° Lat.
~14 km altitude (Tropopause)
Wind speeds of 345-385 kph
Winds flow west to east

Tropical Easterly Jet Stream

Occurs only in the Northern Hemisphere
Associated with the Monsoons in southern Asia and southeast Asia
Winds flow east to west

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