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Home / Which of the Following Locations Experiences the Largest Continuous Belt of Strong Low Pressure

Which of the Following Locations Experiences the Largest Continuous Belt of Strong Low Pressure

Distribution of Air Pressure and Pressure Belts - Geography notes

The worldwide horizontal distribution of pressure refers to the distribution of atmospheric (air) pressure across the latitudes. The most distinguishing aspect is its zonal character, which is referred to as pressure belts. Throughout the year, the Equatorial region receives a lot of heat. The air in the Equator rises because warm air is light, resulting in low pressure. High pressure is created/formed at the poles due to the cold, heavy air. This article will explain to you the Distribution of Air Pressure and Pressure Belts which will be helpful in preparing the Geography Syllabus for the UPSC Civil service exam.

Air Pressure and Pressure Belts

Air Pressure and Pressure Belts

  • The weight of atmospheric components such as dust and air per square centimeter in a specific place is referred to as atmospheric pressure.
  • Vertically, air pressure is maximum near sea level, around 1013.2 Mb, and falls as altitude increases.
  • Pressure belts are areas on Earth that are dominated by either high or low-pressure cells. The atmospheric pressure fluctuates indirectly with temperature in general.
  • Surface pressure and temperature are inversely proportional horizontally. In comparison to low insolation locations like the cold desert and the region, high insolation regions like the equatorial and hot desert regions have low atmospheric pressure.

Distribution of Air Pressure

Distribution of Air Pressure/Atmospheric Pressure

Isobars depict the distribution of atmospheric pressure on a map. An isobar is a hypothetical line constructed between two points with equal atmospheric pressure at sea level.

  1. Vertical Variation of Pressure
  2. Horizontal Variation of Pressure

(a) Vertical Distribution of Pressure

  • Vertical pressure distribution refers to the columnar distribution of air pressure.
  • Although air pressure lowers as the altitude rises, it does not necessarily do so at the same rate.
  • The lowest sections of the atmosphere, near the mean sea level, contain dense components.
Vertical Distribution of Pressure

Vertical Distribution of Pressure

(b) Horizontal Distribution of Pressure

  • On the surface of the planet, pressure gradients are tiny, yet even a slight change in pressure has a big impact on wind speed and direction.
  • Isobars are used to study the horizontal distribution of atmospheric pressure.
  • One or more isobars surround the low-pressure system, with the lowest pressure in the center.
  • High pressure is similarly encased by one or more isobars, with the highest pressure at the center.
  • We study the isobars of January and July because they are the wettest months of the year for a huge area of the globe.
Horizontal Distribution of Pressure

Horizontal Distribution of Pressure

Pressure Belts

Pressure Belts

  • Pressure belts are areas on Earth that are dominated by either high or low-pressure cells. On the surface of the Earth, the high and low-pressure belts alternate. The atmospheric pressure fluctuates indirectly with temperature in general.
  • There are seven pressure bands on the earth's surface.
  • The Equatorial Low, two Subtropical Highs, two Subpolar Lows, and two Polar Highs comprise the four.
  • The others, with the exception of the Equatorial low, form matching pairs in the Northern and Southern Hemispheres.
  • Over the world, there is a pattern of alternate high and low-pressure belts.
  • This is related to the earth's spherical form, which causes uneven heating in different places of the globe.
  • Throughout the year, the Equatorial region receives a lot of heat.
  • The air in the Equator rises because warm air is light, resulting in low pressure.
  • High pressure is created/formed at the poles due to the cold, heavy air. It's also because of the earth's rotation.
  • The rotation of the globe drives the bulk of the air towards the Equator in the Subpolar zone about latitudes 60° to 65° North and South of the Equator, creating a low-pressure belt in this region.
Pressure Belts of the Earth

Pressure Belts of the Earth

Equatorial Low-Pressure Belts

  • From 0 to 5 degrees north and south of the Equator, this low-pressure belt exists.
  • There is a lot of heat here because of the sun's vertical rays.
  • As a result of the convection current, the air expands and rises, causing low pressure to occur here.
  • Because it is a zone of complete quiet with no breeze, this low-pressure belt is also known as the doldrums.

Subtropical High-Pressure Belts

  • The location where the ascending equatorial air currents drop is located around 30° North and South of the Equator.
  • As a result, this is a high-pressure zone.
  • The Horse latitude is another name for it.
  • Winds are continually blowing from high to low pressure.
  • As a result, trade winds blow from the subtropical zone towards the Equator.

Circum Polar Low-Pressure Belts

  • Circum Polar Low-Pressure Belts are belts that run between 60° and 70° in each hemisphere.
  • The descending air in the Subtropical zone is split into two portions.
  • One part of the wind is directed toward the Equatorial Low-Pressure Belt.
  • The remaining half of the wind is directed towards the Circumpolar Low-Pressure Belt.
  • The rise of warm Subtropical air above frigid polar air moving from the poles defines this zone.
  • The winds that encircle the Polar area blow towards the Equator due to the earth's rotation.
  • The Circumpolar Low-Pressure Belt is a low-pressure belt created by centrifugal forces occurring in this region.
  • During the winter, this area is known for its strong storms.

Polar High-Pressure Areas

  • Temperatures are always exceptionally low between 70° and 90° North and South at the North and South Poles.
  • High pressures from above the Poles due to the chilly descending air.
  • The Polar Highs are these areas of high pressure in the Arctic.
  • Permanent IceCaps describe these locations.

Shifting of Pressure Belts

Shifting of Pressure Belts

  • The pressure belts would not exist if the planet had not been tilted towards the sun.
  • However, this is not the case because the earth is inclined 23 1/2 degrees to the sun.
  • Because of this tilt, the warmth of the continents, oceans, and pressure conditions vary dramatically between January and July.
  • In the Northern Hemisphere, January denotes winter, and July denotes summer. In the Southern Hemisphere, the opposite is true.
  • The pressure belts shift 5° northward when the sun shines vertically overhead on the Tropic of Cancer (21 June), and 5° southward when the sun shines vertically overhead on the Tropic of Capricorn (22 December) from their initial position.
  • Seasonal climate fluctuations are caused by the movement of the pressure belts, especially between the latitudes of 30° and 40° in both hemispheres.
  • Because of the changing of permanent belts southwards and northwards with the overhead position of the sun, this region has a Mediterranean climate.
  • During the winter, Westerlies prevail, resulting in rain. During the summer, dry Trade Winds blow offshore, preventing rain from falling in certain areas.
  • The pressure belts in both hemispheres stay balanced when the sun shines vertically over the Equator on March 21st and September 23rd (the Equinoxes).
Shifting Of Pressure Belts

Shifting Of Pressure Belts

Significance

Significance of Pressure Belts

  • Atmospheric pressure is one of the crucial controlling factors of Earth's weather and climate.
  • Atmospheric pressure is an important weather indicator.
  • High-pressure systems generally result in fair and calm weather
  • The seasonal changes in the climate are caused by the shifting of pressure belts.

Conclusion

Conclusion

In some areas between the tropics, pressure and wind belts vary, resulting in a peculiar monsoon phenomenon. Thus, pressure not only is an important element as a separate entity but also as a whole as it influences the remaining elements of the weather and climate like atmosphere, wind, and so on.

FAQs

FAQs

Question: What is atmospheric pressure in simple words?

Answer:

The weight of the Earth's atmosphere, a layer of air, pushes against a surface, creating atmospheric pressure.

Question: What is meant by the horizontal distribution of air pressure?

Answer:

Global horizontal distribution refers to the dispersion of atmospheric pressure across latitudes.

Question: What is the oscillation of pressure belts?

Answer:

The sun's obvious progress causes the pressure belts to oscillate. In the winter, the pressure belt shifts southward, and in the summer, it shifts northward.

MCQs

MCQs

Question: Equatorial low-pressure belt is called' doldrums' because

(a) The atmospheric pressure is exceedingly low.

(b) There are severe horizontal winds in this location.

(c) Only vertical currents may be found because there is no horizontal breeze.

(d) The humidity level in the air is really high.

Answer: (a) See the Explanation

  • The Equatorial Low-Pressure Belt stretches from the equator to latitudes of 5° N and 5° S.
  • The earth is heated at the equator by the vertical sunbeams, which heats the air in contact with it.
  • A low-pressure belt is formed when hot air expands and rises upwards.
  • Due to the lack of surface (horizontal) winds, this belt is known as the doldrums.

Therefore, option (a) is the correct answer.

Question: From the equator to the poles, mark the right order of the pressure belts.

(a) Equatorial low, Sub-Polar low, Polar High, Sub-Tropical High

(b) Sub-Tropical High, Polar High, Sub-Polar low, Equatorial High

(c) Sub-Polar low, Polar High, Sub-Tropical High, Equatorial low

(d) Equatorial low, Sub-Tropical High, Sub- Polar low, Polar High

Answer: (d) See the Explanation

Pressure Belts of the World

Pressure Belts of the World

With the help of the above diagram, it can be understood that the correct order from the equator to the poles is Equatorial low, Subtropical High, Sub- Polar low, Polar High.

Therefore, option (d) is the correct answer.

*The article might have information for the previous academic years, please refer the official website of the exam.

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