Pressure Belts Of The Earth

The earth’s pressure belts are several layers of atmospheric pressure zones that encircle the earth, forming high and low air pressure bands. The tropics are considered to be one large low-pressure belt. The first pressure belt is the subtropical high-pressure belt, which sits on the subtropical jet stream. The subtropical high-pressure belt is an extension of this zone with a band of stronger winds around 30 degrees latitude. These zones directly relate to the distribution and frequency of tropical cyclones in between them. Let us read more about the reasons for the pressure belts in detail in the article. 

Pressure belts on Earth:

(i) Tropical Low-Pressure Belts

This low-pressure belt interfaces from zero to 5° North and South of the Equator. Way to the gentle upward outflows sun-powered here, it might be very warm there. The air, in like way, expands and moves as a convection state, art-making low pressure here. This low-pressure belt is additionally referred to as disillusionment, thinking that it is an area of quiet without a breeze.

(ii) Subtropical High-pressure Belt

The subtropical high-pressure belt is a series of atmospheric pressure zones that form a band located around 30 degrees north and south of the equator. The lines of latitude at which these prominent areas occur are called the subtropical highs. They are an extension of the tropics, mostly found around 0 and 30 degrees latitudes in both hemispheres. The subtropical highs are affected by the jet stream, and they also affect it. The jet stream winds blow towards the west, and a large high-pressure zone is created by this movement in the area of 30 degrees latitude in both hemispheres.

(iii) Sub-Polar Low-Pressure Belts

These pressure belts coordinate a couple of areas inside the extent of 60° and 70° in each half of the area called Circum-Polar Low-pressure Belts. Inside the Subtropical area, the falling air gets allocated into areas. One spot blows toward the Tropical Low-Tension Belt. The elective part blows toward the Circum-Polar Low-Tension Belt. This area is independent with the guide of utilising the rising of hotness Subtropical air over fresh polar air blowing from shafts. Way to the area’s turn, the Polar area’s breezes blow toward the Equator.

(iv) Polar High-Pressure Belts

At the North and South Poles, between 70° to 90° North and South, the temperatures are incredibly low without falling flat. The tainting losing air accomplishes unreasonable tensions over the Shafts. These districts of Polar unreasonable are known as the Polar Highs. These areas are portrayed with the guide of utilising persevering through Ice Covers.

Movement of pressure Belts:

The movement of the pressure belts is differential. In other words, there is no uniform motion in the direction of the zones. They move at different rates in different parts of the globe. Since there are high and low-pressure zones, they move faster toward the poles, especially at higher latitudes.

The movement of the pressure belts is also uneven concerning time. So while some zones are moving faster than others, temperatures never stay constant over even a week or two. There is always some change in the direction and speed of movement.

The rotation of the earth also influences the movement of the pressure belts. However, this does not mean a uniform flow from west to east at every latitude over a year or two.

These pressure belts move toward and away from each other, and they shift certain areas of cloudiness and rainfall fairly routinely. 

The reason behind the presence of pressure belts on the earth’s surface:

1- Heat Absorption By Earth Surface:

According to Newton’s (1642) law of cooling: “All bodies left to themselves become cool. The rate of heat emission from a body at a given temperature depends on its surface area, the material it is made from, and the temperature difference between the body and its surroundings”. 

2- Coriolis Effect:

The earth’s surface rotation produces the Coriolis force, which acts in a direction perpendicular to wind flow. This force deflects winds from their initial path causing cyclogenesis or anticyclogenesis. The pressure belts are separated by Lippmann’s friction height, the distance between 100MB and 700MB.

3- Lifting Mechanism:

Pressure belts are formed as a result of the lifting mechanism. The thermal (advection) mechanism is the lifting that results from the horizontal movement of the air, which is caused by the pressure gradients (drift). The wind moves in the direction to relieve the pressure gradient, and pressure distribution remains constant. In this case, both high and low-pressure zones last for a long time.

Conclusion: 

Pressure belts are a group of clouds that move along the earth’s surface with winds between them. The pressure belts on the earth’s surface move from north to south and from west to east. In addition, the shift in the seasons by shifting in latitude and pole. Earth is surrounded by two sets of pressure belts, one in each hemisphere. The troposphere has all the pressure belts that are formed at different heights. Pressure varies between the belts due to uneven heat distribution on the earth’s surface, Coriolis force (main driving force) and pressure springing.