Atmospheric Pressure

What is Atmospheric Pressure?

Atmospheric Pressure can be defined as an external force that is exerted by the atmospheric column upon a surface due to the gravitational pull of the earth. Atmospheric pressure can be measured using different unit systems such as millimeters of mercury, psi, millibars, kilopascals, and dynes per square centimeter. But mostly, it is commonly measured by using a barometer which consists of a mercury column in a glass tube. We can study the change in atmospheric pressure by the rise or fall of the mercury level with the change in the weight of the atmosphere.

Both atmospheric pressure and winds play a significant role in controlling the Earth's weather and climate and are known as the controlling factors of Earth. Although the atmospheric pressure and winds are different in terms of physical characteristics but are closely associated with each other. 

Here, we have provided a detailed explanation of the pressure and wind system as well as the pressure system of the world which can be taken as a reference by the students for any exam preparation. Also, this article will help them understand the relationship between atmospheric pressure and temperature.

Relation Between Atmospheric Pressure and Temperature

The relationship between atmospheric pressure and temperature is directly proportional to each other. In simple words, increasing temperature causes an increase in the atmospheric pressure and vice-versa.

According to Gay-Lussac's Law, the product of initial pressure (P1) and initial temperature (T1) of a system is equal to the product of its final temperature (T2) and final pressure (P2). 

Mathematically, it is written as P1T1=P2T2 

To understand the relationship better, we can take the example of car tires. During summertime, the increase in the temperature causes the air molecules to move and use up more individual space, resulting in an increase in atmospheric pressure. Whereas, during winter, the air molecules move slowly and are less active, thus using up little space. As a result, the atmospheric pressure decreases.

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What is a Pressure System?

A pressure system of an area can be defined as the rise and fall of the pressure of that particular area of the Earth's atmosphere. This area particularly has a very high or very low pressure when compared to that of the surrounding air. This whole process is known as the pressure system.

Air always moves from high pressure to low pressure due to differences in atmospheric pressure. This difference takes place because there is an expansion in the air while heated and it gets compressed when cooled.

The pressure system can be further divided into two parts:

  1. High-Pressure System

  2. Low-Pressure System

There are also five different pressure systems of the world. They are the following:

  1. Absolute Pressure

  2. Atmospheric Pressure

  3. Differential Pressure 

  4. Gauge Pressure

The readings for these pressure systems are mostly given in the units of millibars. We are all familiar with the importance of atmospheric pressure. It plays a major role in determining the weather condition of a particular area. The change in air pressure accordingly changes the weather conditions. With the rise in air pressure or atmospheric pressure, the weather of an area becomes more clear whereas a fall in the air pressure might result in storms and a cloudy sky.

Did You Know?

1. The reading of all the pressure systems of the world are calculated in millibars.

2.  One atmosphere is equal to 760 millimeters or 1013 millibars.

3. Barometer is the instrument that calculates the atmospheric pressure of the Earth. Hence it is also known as barometric pressure.

4. Gauge Pressure System is the most frequently used pressure system in the world.

FAQs (Frequently Asked Questions)

1. How Does Wind Form?

Ans. The formation of wind occurs when there is a difference in atmospheric pressure of two different areas of Earth's surface. The wind is thus the movement of air from a high-pressure area to a low-pressure area and is caused due to the uneven heating of the earth's surface.

2. What are Surface Winds?

Ans. The winds that surround the surface of the Earth and play a significant role in controlling the weather conditions of an area are known as surface winds. The speed of the surface winds can be measured with the help of an anemometer.