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Pressure system is a location of the Earth's atmosphere that has a particularly high or low pressure compared to the air around it. Pressure can be simply understood as to how far apart the air molecules are. When the air gets squeezed and packed together, it results in high pressure. And when the air is spread apart, that's low pressure. Have you ever wondered why it rains one day while the other day the sun shines bright outside? This unstable weather system is influenced by a number of elements, one of which is the pressure system. In this article, we will look at the various types of pressure systems and the air pressure temperature and density relation.
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Key Takeaways: Pressure Systems, Low-Pressure System, High Pressure System, Atmospheric Pressure, Temperature, Pressure-Belts, Types of Pressure Systems, Applications of Pressure
What are Pressure Systems?
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A pressure system is a region of the Earth's atmosphere with a significantly higher or lower pressure than the surrounding air. We live at the bottom of the atmosphere, and air pressure is the weight of all the air above us. Because the Earth's surface is not evenly heated by the sun, pressure varies from day to day. Warm air rises, resulting in low pressure in areas with warm air known as low-pressure systems. High-pressure systems are on the other hand places with a lot of air pressure.
Pressure Systems
To eliminate pressure differences and achieve equilibrium, air flows from high-pressure zones to low-pressure areas. The Coriolis Effect is caused by the earth's rotation, and it prevents air from traveling in straight lines. In low-pressure systems the wind spirals inwards and upwards; in high-pressure systems, the wind spirals downwards and outwards.
Low-Pressure System
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A low-pressure area is one where the atmospheric pressure at sea level is lower than it is elsewhere. Low-pressure systems originate in areas of wind divergence in the troposphere's upper layers.
Due to localized heating produced by more sunlight over deserts and other landmasses, a low-pressure system forms. Warm air rises as it is less dense in localized locations than the surrounding air, decreasing atmospheric pressure. Pressure gradients that drive monsoon circulations are aided by large-scale thermal lows over continents. A low-pressure system's wind whirl counters clockwise due to the Earth's spin and the Coriolis force in a Cyclic flow.
Low Pressure System
High-Pressure System
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Light winds at the surface and sinking in the lower troposphere are usually linked with high-pressure systems. Subsidence uses adiabatic or compressional heating to dry out an air mass. As a result, high pressure usually means a clear sky. The temperature rises during the day because there are no clouds to block the incoming shortwave solar energy. Because there are no clouds at night, the outgoing longwave radiation is not absorbed, resulting in colder temperatures throughout the year. In contrast to a low-pressure system, a high-pressure system swirls in the opposite way in an anticyclonic flow.
High and Low Pressure System
Read More- Pressure
Atmospheric Pressure Characteristics
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The characteristics of atmospheric pressure are:
- Atmospheric pressure is a measurement of a region's weather conditions.
- Cloudiness, thunderstorms, storms, and cyclonic winds are all caused by low pressure.
- The presence of high pressure helps to the calmness of the weather.
- One atmosphere has a pressure of 1013 millibars (760 millimetres).
The pressure in the atmosphere is a significant environmental component. It has an impact on all three states of matter: solid, liquid, and gas. This atmospheric measure has been used to forecast weather conditions all around the world for many years. The content and chemistry of water are also influenced by atmospheric or barometric pressure. There are five levels to the earth's atmosphere. From top to bottom, they are: Exosphere Thermosphere Mesosphere Stratosphere Troposphere.
Atmospheric pressure
Each of these strata stretches up to a mile in length and is located above sea level. The exosphere is around 700 kilometers above sea level, while the troposphere is about 18 kilometers in the tropical parts and 6-7 kilometers in the Polar Regions. The many atmospheric layers are portrayed in different colors in distinct photographs. The temperature and pressure levels in each of these layers are different.
Air pressure depends on density and temperature
When you are inflating a balloon, the air molecules inside become more closely packed than the air molecules outside. This shows that there is a lot of air inside the balloon. When the density of the air is high, the air pressure is high. Air pressure presses against the balloon from the inside, forcing it to inflate. As the balloon heats up, the air pressure climbs even more.
Air pressure is determined by the temperature of the air and the density of the air molecules. To describe the link between pressure, temperature, density, and volume, atmospheric scientists use arithmetic equations known as Ideal Gas Laws. In these equations, the temperature is represented in Kelvin.
Ideal Gas Law
The ideal gas laws are:
- Pressure = Temperature*Density*Constant
- Pressure*Volume = Temperature*Constant
This equation describes how weather works, how the atmosphere generates cold and warm fronts and produces thunderstorms. When the air pressure rises, the temperature must rise with it. When there is a reduction in air pressure, the temperature also drops. It also explains why, when the pressure drops, the air becomes colder at higher altitudes.
Things to Remember
- A pressure system is a place of the Earth's atmosphere with a significantly higher or lower pressure than the surrounding air.
- We reside at the bottom of the atmosphere, and air pressure is the weight of all the air above us
- A low-pressure area is one where the atmospheric pressure at sea level is lower than it is elsewhere.
- Low-pressure systems originate in areas of wind divergence in the troposphere's upper layers.
- Light winds at the surface and sinking in the lower troposphere are usually linked with high-pressure systems.
- Subsidence uses adiabatic or compressional heating to dry out an air mass. As a result, high pressure usually means a clear sky.
Also Read- Barometer: Definition, Working, Types
Sample Questions
Ques. What are the types of pressure systems? (5 marks)
Ans. Pressure is one of the most essential physical state variables, second only to temperature. Force acting uniformly over a specific region is defined as pressure (A). Only the reference pressure distinguishes the various forms of pressure.
- Absolute Pressure = Pressure zero, which occurs in the universe's airless void, is the clearest reference pressure. Absolute pressure is a pressure that is proportional to this reference pressure.
- Atmospheric Pressure = The atmospheric pressure is arguably the most significant pressure for life on Earth. It is caused by the weight of the atmosphere that surrounds the earth to a height of about 500 kilometers.
- Differential Pressure = The pressure differential is defined as the difference between two pressures, p = p1 - p2.
- Overpressure (gauge pressure) = Overpressure refers to a difference between an absolute pressure, pabs, & the applicable or absolute atmospheric pressure (pe = pabs - pamb). When the absolute pressure exceeds the atmospheric pressure, it is referred to as a positive overpressure. Negative overpressure is the opposite of positive overpressure.
Ques. How does air pressure affect weather? (5 marks)
Ans. The air surrounding you is heavy, and it pushes against everything it comes into contact with. Atmospheric pressure, or air pressure, is the name given to this pressure. To measure this atmospheric pressure, we often use a barometer. When there is a change in the weight of the atmosphere, a column of mercury in a glass tube rises or falls in a barometer. Atmospheric pressure is determined by meteorologists by observing the height up to which the mercury rises.
As height rises, atmospheric pressure decreases. As the pressure drops, so does the amount of oxygen accessible to breathe. At high altitudes, the air pressure and oxygen that is available is so low, that people eventually become sick and can even die.
This is why, when people climb the highest peaks, they often carry bottled oxygen as they take some time getting accustomed to the altitude as going from high to low pressure rapidly can trigger some depression sickness.
Ques. Discuss 5 applications of pressure in daily life. (5 marks)
Ans. Pressure has important applications in our daily life which are:
(a) When humans breathe, the air pressure of 15 pounds per square inch at sea level allows oxygen to easily pass through the semipermeable barrier. If the same activity is performed at a greater altitude, the reduced air atmospheric pressure may result in hypoxia or oxygen deprivation.
(b) The ink dropper that we use on a daily basis is based on the notion of air pressure. The ink rushes in to fill in the void as soon as we produce a low pressure by getting rid of the air inside the bulb.
(c) A jet liner's cabin pressurization is maintained above 10,000 feet by pumping compressed air into it to compensate for the low pressure outside. If not done, high blood pressure inside the blood vessels compared to low pressure will cause them to bulge and burst open, resulting in bleeding from the nose and ears.
(d) The suction created by plungers in sinks is based on the same idea of having lower pressure within than outside, and the suction is nothing more than a difference in air pressures.
(e) An airplane would take off from the ground entirely solely on the fact that moving the air lowers the air pressure in the local vicinity, which aids in lifting the plane.
Ques. Is High Pressure always equivalent to Warm Air? (5 marks)
Ans. Cold or warm, humid or dry, high-pressure systems exist. The meteorological characteristics of a high-pressure area are determined by its origin.
When high pressures develop, they take on the characteristics of the source regions they pass through. Polar air masses are cold, high-pressure air masses that originate in polar locations. Tropical air masses are warm air masses that originate in the subtropics or the tropics.
A high-pressure system has higher atmospheric pressure than the surrounding areas. High-pressure zones at ground level are usually created by air moving down from above. Subsidence, or sinking air, is detrimental for cloud formation; hence high-pressure systems contain few clouds.
You may have also noticed that while we are under the influence of a high-pressure system, the winds are light. Pollutants pile up in the high due to a lack of breeze, resulting in poor air quality. Few clouds also indicate plenty of sunshine, which, along with summer's mild temperatures, is beneficial to ozone generation at the ground level.
Ques. What are the Different Pressure Belts of Earth? (5 marks)
Ans. The different belts of the Earth are:
(i) 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.
(ii) Subtropical High-Pressure Belts
The location where the ascending equatorial air currents drop is located around 30° North and South of the Equator. 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 from the subtropical zone blow towards the Equator, whereas Westerlies blow towards Sub-Polar Low-Pressure.
(iii) 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.
(iv) Polar High-Pressure Areas
Temperatures are always exceptionally low between 70° and 90° North and South at the North and South Poles. High pressures form 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.
Ques. State an experiment to describe the effect of air pressure. (5 marks)
Ans. Experiment with an Indoor Tornado
You can create a tornado in a bottle with this experiment. You'll need the following items:
- Water
- A clear container of mayonnaise
- Dishwashing liquid
- Food color
- Vinegar
Procedure:
- Fill your jar with water about two-thirds full. Then, in a separate bowl, add a few drops of food coloring to the water. Any color will suffice.
- Add one teaspoon of liquid dish soap and vinegar to the mix.
- Cover the jar with the lid. To avoid leaks and major messes, make sure it's on as tightly as possible.
- Shake the jar and then twist it so that the liquid inside begins to spin.
Observation:
You'll see a little vortex that looks like a tornado.
Ques. What are Low-Pressure Systems also Known as? (5 marks)
Answer. Low-pressure systems, often known as cyclones, are a type of low-pressure system. A surface low-pressure center is a location where the pressure is the lowest in relation to its surroundings. That is, traveling away from the Low in any horizontal direction will result in increased pressure. The centers of mid-latitude cyclones are frequently represented by low-pressure centers.
On a weather map, a low-pressure center is depicted by a red L. In the northern hemisphere, winds move counterclockwise around the low. In the southern hemisphere, where winds travel clockwise around a low-pressure depression, the converse is true. The counter-clockwise winds associated with northern hemisphere mid-latitude cyclones play an important role in the movement of air masses, carrying warm wet air northward ahead of a low while pushing colder, drier air southward behind it.
Ques. Why are Hurricanes Low Pressure Systems? (3 marks)
Ans. Hurricanes are ferocious meteorological occurrences that feed off the heat of tropical waters. These severe storms often start as a tropical wave, which is a low-pressure system that sweeps through the moist tropics, potentially boosting shower and thunderstorm activity.
The warm air of the ocean rises into the storm, it advances westward across the tropics. This generates a region of low pressure beneath it. Therefore, more air rushes in. As this air rises and cools down, thunderstorms and clouds are formed. Water condenses to form droplets, thereby releasing more heat, fuelling the storm more.
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