Global pressure belts

Global pressure belts

Pressure

If the pressure in a region is more than that of its surroundings, then we say that it is high pressure there and if it is less, we say that it is low pressure.

Global pressure belts

Generally, the earth experiences the same atmospheric pressure between certain

latitudes. These latitudinal zones are called global pressure belts.

Differences in the amount of solar radiation experienced over different parts of the earth cause the formation of different pressure belts. 

Following are the different pressure belts of the earth.

1. Equatorial low-pressure belt

2. Subtropical high-pressure belt (Northern Hemisphere)

3. Subpolar low-pressure belt (Northern Hemisphere)

4. Polar high-pressure belt (Northern Hemisphere)

5. Subtropical high-pressure belt (Southern Hemisphere)

6. Subpolar low-pressure belt (Southern Hemisphere)

7. Polar high-pressure belt (Southern Hemisphere)

Equatorial low-pressure belt

This pressure belt extends up to about 5° to 10° on either side of the equator. Here the high temperature is experienced throughout the year. Haven't you understood that as the temperature rises pressure decreases? It means that as a result of the higher temperature here the air expands and rises vertically. This is the reason for the formation of low pressure in this region. This low-pressure region characterised by a low horizontal movement of air is called doldrums. 

This pressure belt is also known as 'doldrum', meaning 'the zone with no winds'. The region was a nightmare for the ancient mariners.

Subtropical high-pressure belts

Subtropical high-pressure belts extend approximately over 30° north and south

latitudes. High-pressure belts develop over here as the hot air that rises up from the equatorial regions gets deflected due to the Coriolis effect and concentrates in these regions.

Horse latitude

Superior breeds of horses were once a major export from Europe to America and Cargo ships were used to carry them across. As the winds are feeble in the subtropical regions, it was difficult for these ships to sail smoothly. In order to make the ship lighter to facilitate easy voyage, they used to throw many of these horses into the sea. Thus the zone acquired the name ‘horse latitude’.

Subpolar low-pressure belts

Subpolar low-pressure belts extend approximately over 60° north and south

latitudes. These are regions where low temperature is experienced. As a result of the strong Coriolis effect in this region winds blowing from the polar regions are deflected away. Hence this exists as a low-pressure region.

Polar high-pressure belts

Since the temperature received in this region is the lowest, the air would be cooler. Cold air exerts a high pressure here. Along with this, the air deflected from the subtropical belt is concentrated here. This is the reason why polar regions have developed into high-pressure belts.

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👉 Weather and Climate
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👉 The atmosphere 
👉 Geography - Questions and Answers 

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