Pressure belts of the World
There is a relationship between temperature and the atmospheric pressure of place. This is not uniform everywhere in the world. As some places on the earth have low pressure and some places on the earth have high pressure. This is greatly modified by the rotation of the earth.
These permanent pressure belts are unstable as they shift northward during summer and southwards during winter. This is caused by the movement of the sun between the Tropic of Cancer and the Tropic of Capricorn.
There are four major Permanent pressure belts of the World
- Equatorial Low-Pressure Belt (5° N to 5° S)
- Sub-Tropical High-Pressure Belt ( (30° N & S to 35° N & S)
- Sub-Polar Low-Pressure Belt ( (60° N & S to 65° N & S)
- Polar High-Pressure Belt ( (90° N & S)
The Doldrum is also called equatorial low. It lies along the Equator and at a range of 5° north and south. This is an equatorial low-pressure belt. Here the temperature is high throughout the years.
Due to the high temperature, the air rises and expands, which causes this low-pressure belt.
Sub-Polar Low-Pressure Belt
This lies in the range of 60° and 65° north and south latitudes. The low pressure is caused due to the rotation of the earth. These are caused by the air that moves from high-pressure polar areas also from the air that comes from the subtropical high-pressure areas.
These two air meets at 60° North and 60° South latitudes. This makes the air rise and causes a low-pressure belt in these regions.
Sub tropical High Pressure Belt
These lie in the latitude of 30-35° North and 30-35° South of the Equator. This over here raises up due to heating moves towards the Poles. But this warm air cools down and sinks at 30° North and 30° South latitudes. Here it piles up to create high-pressure belts.
This sub-tropical high pressure is also called Horse Latitudes.
Polar High-Pressure Belt
Polar High-Pressure belts lie near the poles. This region is extremely cold. This makes the air cold, dense, and Heavy. The accumulation of heavy air in this region causes High-Pressure Belt.
This location is not fixed and moves towards the south and north as per the position of the Sun.
1.Equatorial low-pressure belt is called?
It is called Doldrum. It is because it is a zone of total calm without any breeze. Here the air circulated in an upward direction and there is only little surface wind in ITCZ. The sailors know this are is calm for sailing ships for weeks.