world pressure pelt

world pressure pelt

TYPES OF PRESSURE BELT

i ) Equatorial low pressure belt

ii) Sub tropical low pressure belt

iii) Circum polar low pressure belt

iv) Polar high pressure belt

shifting of pressure belt

If the earth had not been inclined towards the sun, the pressure belts, as described above, would have been as they are. But it is not so, because the earth is inclined 23 1/2° towards the sun. On account of this inclination, differences in heating of the continents, oceans, and pressure conditions in January and July vary greatly. January represents winter season and July, summer season in the Northern Hemisphere. Opposite conditions prevail in the Southern Hemisphere.

to be continued

When the sun is overhead on the Tropic of Cancer (21 June) the pressure belts shift 5° northward and when it shines vertically overhead on Tropic of Capricorn (22 December), they shift 5° southward from their original position. The shifting of the pressure belts causes seasonal changes in the climate, especially between latitudes 30° and 40° in both hemispheres. In this region, the Mediterranean type of climate is experienced because of the shifting of permanent belts southwards and northwards with the overhead position of the sun.

to be continued

During winters Westerlies prevail and cause rain. During summers dry Trade Winds blow offshore and are unable to give rainfall in these regions. When the sun shines vertically over the Equator on 21st March and 23rd September (the Equinoxes), the pressure belts remain balanced in both the hemispheres.