Our planet is covered with alternating high and low pressure belts. The difference in pressure belts arises due to varying temperature distribution around the earth.As sun rays falls directly over the equator the air gets heated and it rises causing low pressure where as in the polar region the cold air sinks and it causes high pressure. around the sub polar region between latitudes 60 degree north and 65 degree south of the equator,the rotation of the earth flings the air towards the equator creating low pressure belt.
THE 4 MAJOR TROPICAL BELTS ARE:
EQUATORIAL REGION LOW PRESSURE BELT: This belt extendes from latitude 5 degree north to 5 degree south of the equator.as the air here is warmer it rises and forms low pressure known as doldrums.
SUB TROPICAL HIGH PRESSURE BELTS: It extends from latitude 30 degree north and 30 degree south of latitude.the air which rises in the former meets the tropopause and cools down making it a high pressure area.this area is marked by strong winds.Air flings in this region due to the rotation of the earth.
SUB POLAR PRESSURE BELTS:it is a low pressure belt around latitude 60 degree north and 65 degree south of the equator.Its low pressure is due to rotation of the earth which swings bulk of air towards the equator.
POLAR REGION BELTS: HIGH pressure belt due to bulk of extremely cold air located in the polar region.