Global Winds

GLOBAL PRESSURE

EQUATORIAL LOW

POLAR FRONT (LOW PRESSURE) (60°)

TROPICAL HIGH (30°)

POLAR HIGH

•Global circulation depends on differential heating over the globe.

• The system is driven by strong equatorial heating, causing LOW PRESSURE.

•Equatorial air rises, diverges and descends over the tropics, where HIGH PRESSURE dominates; where it diverges at ground level.

•This tropical air blows towards the equator, completing the equatorial cell, or towards the mid-latitides where it meets cold, dense polar air blown out from the polar HIGH PRESSURE.

•These contrasting tropical and polar air masses meet at the POLAR FRONT LOW PRESSURE BELT, where the warmer air is forced upwards by the polar air.

•At high level, this air again diverges towards the pole or to the tropic.

•Global circulation depends on differential heating over the globe.

• The system is driven by strong equatorial heating, causing LOW PRESSURE.

•Equatorial air rises, diverges and descends over the tropics, where HIGH PRESSURE dominates; where it diverges at ground level.

•This tropical air blows towards the equator, completing the equatorial cell, or towards the mid-latitides where it meets cold, dense polar air blown out from the polar HIGH PRESSURE.

•These contrasting tropical and polar air masses meet at the POLAR FRONT LOW PRESSURE BELT, where the warmer air is forced upwards by the polar air.

•At high level, this air again diverges towards the pole or to the tropic.

The Hadley Cell has air which rises at the equator (low pressure) and sinks at 30° latitude (high pressure)

The resulting wind (which goes from high to low) is curved due to the Coriolis effect

GLOBAL PRESSURE BELTS & WIND

EQUATORIAL LOW

TROPICAL HIGH PRESSURE

TROPICAL HIGH PRESSURE

POLAR FRONT - LOW PRESSURE

POLAR HIGH PRESSURE

POLAR HIGH PRESSURE

GLOBAL WIND BELTS (trade winds) are controlled by the major pressure belts, which are produced from differences in temperature and the spinning of the Earth.

POLAR FRONT - LOW PRESSURE

H

H

H

H

L

L

L

GLOBAL PRESSURE BELTS AND THE TRADEWINDS

GLOBAL WINDS AND

AIR CIRCULATION

GLOBAL WINDS, CELLS, AND AIR CIRCULATION

The primary circulation cells are called: The Polar CellThe Ferrel Cell and The Hadley Cell

The circulation of the air and resulting winds are formed from differential heat and the spinning of the Earth which creates the permanent High and Low pressure regions