Atmosphere Contents

5. General Circulation

As the air moves poleward from the tropics it constantly cools by radiation

As the air cools in its poleward movement from the tropics, it also begins to converge (pile up), especially as it approaches the middle latitudes. This increases the mass of air above the surface, which in turn causes the air pressure at the surface to increase producing belts of high pressure called subtropical highs (or anticyclones) at latitudes near 30°. The air then starts to descend at this latitude, called the horse latitudes, producing an area of generally clear skies and warm surface temperatures, where the major deserts of the world are found.

Poleward movement

What happens as air moves poleward from the tropics?