Climatology for Kerala PSC: Global Pressure Belts
June 24, 2022 2022-06-24 11:09Climatology for Kerala PSC: Global Pressure Belts
Atmospheric pressure on the earth’s surface is not uniform. It varies from place to place. It is influenced by the temperature of the air at a given place.
● But on a global scale, there are a few permanent pressure belts. they are:
1. Equatorial Low-Pressure Belt
2. Subtropical high-Pressure Belt
3. Subpolar Low-Pressure Belt
4. Polar High-Pressure Belt
Equatorial Low-Pressure Belt
● The temperature is high throughout the year near the equator.
● As a result, the lower layers of the atmosphere get heated. Air expands and rises continuously in this region.
● As a result, a low-pressure belt is created in this region. It is known as the. Equatorial Low-Pressure Belt.
● Since winds are weak here the zone is also known as Doldrums
Subtropical high-Pressure Belt
● The rising air at the equator cools down after reaching the upper parts of the atmosphere.
● This air spreads out towards the poles and starts sinking near 30°N and 30°S latitudes and piles up there.
● Thus, high-pressure belts are produced in these regions. They are known as the Subtropical High-Pressure Belt or horse latitudes.
● The subsiding air is relatively dry because its moisture has already been released near the equator.
● Consequently, the world’s tropical deserts are located in this belt.
● As soon as the subsiding air reaches – the earth’s surface, it splits into two branches.
● One start flowing towards the Pole and the other towards the equator.
Subpolar Low-Pressure Belt
● In both the hemispheres, the air moving from the two high-pressure belts i.e., polar and the subtropical high-pressure belts, meet each other near 60° latitude.
● Converging air starts rising and a low-pressure belt is created named sub-polar low-pressure belt.
● Sub-polar low-pressure belts are developed near 60°N and 60°S latitudes.
Polar High-Pressure Belt
● The air is very cold throughout the year in the North and South poles. Therefore, the air is dense and heavy.
● As a result, it keeps on piling up. This produces a high-pressure belt around the two Poles. It is known as Polar High-Pressure Belt