4.5 Global Wind Patterns

Explain global wind circulation patterns

Air heated at the surface in the lower latitudes (subtropics, tropics) rises and gets replaced by cooler, denser air flowing from the higher latitudes (poles)

What are the three convection cells present in each hemisphere?

- Hadley Cell

- Ferrell Cell

- Polar Cell

Hadley Cell

- (0-30 degrees North or South)

- Air heats up at equator and rises northward, where the air becomes dense enough to sink

- Most of the air flows back toward the equator, deflecting westward

Ferrell Cell

- (30-60 degrees North or South)

- Wind from the Hadley cell that does not return to the equator continues toward the poles shifting right in Northern Hemisphere or left in the Southern Hemisphere

Polar Cell

- (60-90 degrees North or South)

- Once moving air reaches the poles, the air sinks, moving southward (in Northern Hemisphere) or northward (in Southern Hemisphere)

What pressure area occurs after hot air rises? after cool air sinks?

- Rising air: low pressure area

- Sinking air: high pressure area

Name the four different pressure belts

- Equatorial Low

- Subtropical High

- Sub-Polar Low

- Polar High

Equatorial Low

- (0 degrees)

- Region of low pressure associated with warm air raising at the equator

Subtropical High

- (30 degrees North and South)

- Region of high pressure associated with sinking air

Sub-Polar Low

- (60 degrees North and South)

- Region of low pressure associated with the polar front

Polar High

- (90 degrees North and South)

- Region of high pressure associated with cold, dense sinking air from the poles

Explain the Coriolis Effect

The deflection of wind in the Northern Hemisphere to the right (clockwise) and in the Southern Hemisphere to the left (counterclockwise)

Name the three different wind belts

- Trade Winds

- Prevailing (Westerlies) Winds

- Polar Winds

Trade Winds

(0-30 degrees)

- Northeast trade winds

- Southeast trade winds

Prevailing Winds (Westerlies)

(30-60 degrees)

- Prevailing North Westerlies

- Prevailing South Westerlies

Polar Winds

(60-90 degrees)

- Polar Southeasterlies

- Polar Northeasterlies