What do you mean by atmospheric pressure? What is its value on the surface of Earth?

Atmospheric pressure refers to the force exerted by the weight of the air present in the atmosphere on the surface of the Earth. The air around us has weight, and this weight creates pressure on every object, including our bodies, buildings, and land. This pressure is known as atmospheric pressure.

Air is made up of different gases, and due to the gravitational pull of Earth, these gases exert a downward force. As we move higher, like climbing a mountain, the atmospheric pressure decreases because there is less air above us.

Standard atmospheric pressure at sea level is approximately:

• 101.3 kilopascals (kPa)

• 1 atmosphere (atm)

• 76 cm of mercury (Hg)

• 760 mm of Hg

This means that at sea level, the weight of the air presses down on each square centimetre of surface with a force equal to the weight of a 76 cm tall column of mercury.

Example to Understand:

You can imagine atmospheric pressure like the weight of a big stack of air on your head, but you don’t feel it because your body’s internal pressure balances it out.