Name the world’s pressure belts.?
Answers
Explanation:
Pressure Belts of Earth. On the earth's surface, there are seven pressure belts. They are the Equatorial Low, the two Subtropical highs, the two Subpolar lows, and the two Polar highs.
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Answer:
EQUATORIAL LOW PRESSURE BELT - DEFINITION
It exists between 5
0
N to 5
0
S of the Equator. This is also called the belt of calm as there is hardly any surface wind. This region gets the vertical rays of the Sun all through the year which leads to the expansion of air. Lighter air ascends and it creates convection currents in the atmosphere. The low pressure belt is the result of these ascending currents. These currents carry moisture along with them which causes rainfall almost everyday in the equatorial region.
SUBTROPICAL HIGH PRESSURE BELT - DEFINITION
It exists closer to the Tropic of Cancer and the Tropic of Capricorn between 30
0
to 35
0
N and S of the Equator. It is comparatively cooler here than in the equatorial region.
SUB POLAR LOW PRESSURE BELT OR CIRCUM POLAR LOW PRESSURE BELT - DEFINITION
These pressure belts are located between 60
0
N and 65
0
S of the Equator. These two regions are cold and known for cyclones and storms. This belt has low pressure due to the rotation of the Earth. Here, most of the air swings towards the Equator. The envelop of air is also quite thin due to air being thrown towards polar high and subtropical high pressure belt.
WORLD PRESSURE BELTS AND NAME ITS TYPES - DEFINITION
The distribution of atmospheric pressure across the latitudes is termed global horizontal distribution of pressure. There is a pattern of alternate high and low pressure belts over the earth. These belts are as under:
1. Equatorial low pressure belts
2. Sub-tropical high pressure belts
3. Circum-polar low pressure belts
4. Polar high pressure areas
POLAR HIGH PRESSURE BELT - DEFINITION
This belt exists between 70
0
N to 90
0
S of the Equator due to extremely cold conditions. The low temperature makes the air dense and it sinks creating a high pressure region. The ice rarely melts in these areas, that too only in patches.
EQUATORIAL LOW PRESSURE BELTS - DEFINITION
This low pressure belt extends from 0 to 5
0
North and South of Equator. Due to the vertical rays of the sun here, there is intense heating. The air therefore, expands and rises as convection current causing a low pressure to develop here. This low pressure belt is also called as doldrums, because it is a zone of total calm, i.e., without any breeze.
SUBTROPICAL HIGH PRESSURE BELTS - DEFINITION
At about 30
0
North and South of Equator lies the area where the ascending equatorial air currents descend. This area is thus an area of high pressure. It is also called the Horse Latitude. Winds always blow from high pressure to low pressure. So the winds from sub tropical region blow towards Equator as Trade Winds and another wind blows towards Sub-Polar Low Pressure as Westerlies.
CIRCUM-POLAR LOW PRESSURE BELTS - DEFINITION
These belts located between 60
0
and 70
0
in each hemisphere are known as Circum-polar Low Pressure Belts. In the Sub-tropical region the descending air gets divided into two parts. One part blows towards the Equatorial Low Pressure Belt. The other part blows towards the Circum-polar Low Pressure Belt. This zone is marked by ascent of warm sub-tropical air over cold polar air blowing from poles. Due to earth's rotation, the winds surrounding the polar region blow towards the Equator. Centrifugal forces operating in this region create the low pressure belt appropriately called Circum-polar Low Pressure Belt. This region is marked b violent storms in winter.
POLAR HIGH PRESSURE AREAS - DEFINITION
At the North and South Poles, between 70
0
to 90
0
North and South, the temperatures are always extremely low. The cold descending air gives rise to high pressures over the Poles. These areas of high pressure are known as the Polar Highs. These regions are characterised by permanent Ice Caps.
SHIFTING OF PRESSURE BELTS - DEFINITION
If the earth had not been inclined towards the sun, the pressure belts, as described above, would have been as they are. But it is not so, because the earth is inclined 23
2
1
0
towards the sun. On account of this inclination, differences in heating of the continents, oceans and pressure conditions in January and July vary greatly. When the sun is overhead on the Tropic of Cancer (June 21) the pressure belts shift 5
0
northward and when it shines vertically overhead on Tropic of Capricorn (22 December), they shift 5
0
southward from their original position.