Why do the wind and pressure belts migrate seasonally?
The dynamic causes of these zones, or belts, of high and low pressure are more complex than the ther- mal causes. These dynamic causes are related to the rotation of Earth and the broad patterns of circulation. For example, as air rises steadily at the equator, it moves toward the poles.
Prevailing winds and pressure belts are major climate controls. A belt of low pressure known as the intertropical convergence zone (ITCZ) lies along the Equator. On either side of the equatorial low, between 25° and 30° latitude in each hemisphere, is a belt of high-pressure centers over the oceans.
- The subtropical ridge, also known as the subtropical high or horse latitudes, is a significant belt of atmospheric high pressure situated around the latitudes of 30°N in the Northern Hemisphere and 30°S in the Southern Hemisphere.
- While crossing the Equator, sailors in the 1700's would often get their boats stuck due to lack of wind. They called this area the doldrums. The doldrums, or ITCZ, are part of the general circulation system of the Earth. These winds that get more moist and warm as they travel to the Equator meet at the doldrums.
- Wind is caused by differences in the atmospheric pressure. When a difference in atmospheric pressure exists, air moves from the higher to the lower pressure area, resulting in winds of various speeds. On a rotating planet, air will also be deflected by the Coriolis effect, except exactly on the equator.
Updated: 21st November 2019