Pressure Belts: Definition and Meaning

In our atmosphere, there are dozens phenomena that keep happening round the year, which directly or indirectly affect us and decide our activities and life-style. However, all such activities are not independent form each other, but rather dependent on each other. Pressure belts are one such region that define and decide atmospheric activities on global scale.

What are Meaning of Pressure Belt?

Pressure belts define the region in the earth’s atmosphere where air pressure is relatively homogenous or uniform. Such regions usually characterized as either ‘Low’ or ‘High’ pressure belt. These pressure belts form due to the complex interactions among the solar radiation, earth’s rotation, and geographical distribution of land and oceans. All these different features have different capacity to observe, hold, and release heat and because of such different heating and cooling properties, distinct pressure systems develop.

Major Pressure Belts of the World

Following are the major pressure belts that covers entire planet earth:

• Equatorial Low Pressure Belt

  Also known as Intertropical Convergence Zone (ITCZ), the equatorial low pressure belt is located between 100 N and 100 S of equator (i.e. 00). This is the region where sun’s rays fall vertically round the year and because of the consistent straight sun’s rays, air steadily gets warm and rises up causing low pressure. Further, because of excessive heating there is hardly any horizontal movement of air and only conventional currents can be seen.

  Interestingly, because of this calm feature in the region, people also call it doldrums (means, zone of calm). Secondly, this the region where wind coming from sub-tropical high pressure region of north and as well as south converge here; this is the reason, it is also called as Intertropical Convergence Zone. A frequent rainfall can be observed here in the afternoon.

• Sub-tropical High Pressure Belts

  The sub-tropical High Pressure Belts are located roughly between 150 and 350 in both the hemisphere (northern hemisphere and southern hemisphere). So, in the northern hemisphere, it is known as “northern sub-tropical high pressure belt” and in the southern hemisphere, it is known as “southern sub-tropical pressure belt.” The reason behind having high pressure region is the descend of air that rose up in the equatorial region.

  The equatorial air rising up, after coming at certain height deflects towards poles because of earth’s rotation. In the meantime, it also gets cool and heavy, so starts descending in this sub-tropical region and makes high pressure system. After descending, the air diverges in both north and south directions. In the northern hemisphere, the wind rushing towards north goes to sub-polar low pressure belt and in the south direction, the wind rush towards equatorial low pressure belt.

  On the contrary, in the southern hemisphere, the wind rushing towards south, goes to sub-polar low pressure belt and the wind running towards north goes to equatorial low pressure belt. Related to this high pressure zone, there is an interesting story i.e. during the olden days, vessels with cargo of horses, passing through this region, used to face difficulty in sailing in this zone. The pressure compelled them to unburden their vessels and therefore, they used to throw the horses to make their vessels lighter. And, because of this reason, this belt is known as ‘horse latitudes.’

• Sub-Polar Low Pressure Belts

  The sub-polar low pressure belts roughly fall between 450 and 700 in the northern hemisphere as well as in the southern hemisphere. This value is variable, as depends upon the position of the Sun. In the norther hemisphere, it is known as “north sub-polar low pressure belt” and in the southern hemisphere, it is known as “south sub-polar low pressure belt.” Winds coming from sub-tropical high pressure region and polar high pressure region converge here. Likewise, this zone of convergence is known as polar front.

• Polar High Pressure Belts

  Around the polar regions, (both around the north pole as well as around south pole), high pressure belts occur. This is the region that receive slanting sun’s rays throughout the year, resulting very low temperature (always measured in minus). So, because of low temperature, air gets compressed and resultantly the density increases, which ultimately causes high pressure belt here. In the northern hemisphere, it is known as north polar high pressure belt; on the other hand, in the southern hemisphere, it is known as south polar high pressure belt. Winds from these regions move towards sub-polar low pressure belts in both the hemisphere.

Role of Pressure Belts in Shaping Weather Patterns and Climate

Pressure belts have substantial and critical role in determining weather patterns and climate zones across the globe as:

• Wind Patterns − Movement of winds and its patterns is exclusively decided by pressure belts, as wind blows from high pressure areas to low pressure areas. This system of winds creates prevailing wind directions that ultimately influence weather patterns and climates.

• Rainfall and Precipitation − Pressure belts are critical elements that influence the distribution and intensity of rainfall and precipitation. Regions around the equatorial low pressure belt consistently experience heavy rainfall, while areas near the subtropical high pressure belts are often dry and arid; occasionally experience any rainfall.

• Climate Zones − As the arrangement and location of pressure belts are highly fixed and regular, it contributes to the formation of distinct climate zones, such as equatorial, tropical, subtropical, temperate, polar climates, etc. Each of them have unique and distinct temperature, humidity, and precipitation patterns.

• Tropical Cyclone and Hurricanes − Cyclone and Hurricanes are the direct products of the interplay of different pressure belts and temperature variations in tropical regions.

Impact of Pressure Belts on Human Activities

Most of the human activities such as agriculture, transportation, and trade. In fact, having the knowledge of pressure belts and understanding of associated phenomena help to optimize resource management and enhance the safety in aviation and maritime operations.

Conclusion

As we discussed above, pressure belts determine the global circulatory system of the atmosphere, orchestrate the intricate movement of air masses that ultimately shape weather patterns and climates around the globe. Starting from the equatorial low pressure belt’s sparkling thunderstorms to the subtropical high pressure belt’s clam skies, and turbulent sub-polar low pressure belt’s cyclone and anti-cyclone, each pressure belt plays crucial role in maintaining the Earth’s atmospheric balance.

Frequently Asked Questions

What are pressure belts, and how are they formed in the Earth's atmosphere?

Pressure belts are vast regions in the Earth's atmosphere where air pressure is relatively uniform. They are formed due to the differential heating and cooling of the Earth's surface, resulting in variations in air density and pressure.

How many major pressure belts are there, and where are they located?

There are five major pressure belts encircling the Earth. They are the Equatorial Low Pressure Belt, the Subtropical High Pressure Belts, the Subpolar Low Pressure Belts, the Polar High Pressure Belts, and the Polar Low Pressure Belts.

What is the role of pressure belts in driving global wind patterns?

Pressure belts play a significant role in driving global wind patterns. Air flows from regions of high pressure to regions of low pressure, creating prevailing wind directions that influence weather patterns and climate.

How do pressure belts impact rainfall and precipitation distribution?

Pressure belts influence the distribution of rainfall and precipitation. Regions near low-pressure belts, such as the equatorial zone, experience heavy rainfall, while areas near high-pressure belts, like the subtropics, are often dry and arid.

How do pressure belts contribute to the formation of different climate zones?

The arrangement of pressure belts contributes to the formation of distinct climate zones. Tropical, subtropical, temperate, and polar climates are shaped by the positioning and characteristics of pressure belts.

Do pressure belts have any influence on the formation of tropical cyclones and hurricanes?

Yes, pressure belts, along with temperature variations in tropical regions, provide the necessary conditions for the formation of tropical cyclones and hurricanes.

How do pressure belts impact human activities, such as agriculture and transportation?

Pressure belts influence human activities by affecting weather patterns. Understanding pressure belt-related weather conditions helps optimize agricultural practices, plan transportation routes, and ensure safe aviation and maritime operations.

Can pressure belts shift or change their positions over time?

Yes, pressure belts can shift or change their positions due to various factors, including seasonal changes and natural climate variability. Long-term climate change may also influence the positioning of pressure belts.

Do pressure belts play a role in the global water cycle?

Yes, pressure belts are an integral part of the global water cycle. They influence atmospheric circulation and the movement of air masses, which, in turn, impacts the distribution of moisture and precipitation around the Earth.

How do scientists study pressure belts and their effects on weather and climate?

Scientists study pressure belts through a combination of satellite observations, weather monitoring stations, and computer models. These tools help analyze atmospheric conditions, wind patterns, and weather phenomena related to pressure belts.