6.6 Atmospheric Pressure
The Earth is surrounded by a layer of air which we call the atmosphere. Air is a mixture of gases. Their molecules are always in motion. They collide with one another and with all other objects coming in their way. Thus, they exert force on the objects. This force per unit area is the atmospheric pressure. Since the molecules of air have random motion, atmospheric pressure acts equally in all directions.
lightbulbThe atmosphere exerts pressure on the surface of the Earth and on everything on the Earth. This pressure is called atmospheric pressure.
Atmospheric pressure extends up to a height of about 100 kilometres. The density of air is not the same throughout the atmosphere; it decreases continuously with altitude.
We live at the bottom of the Earth's atmosphere, which is a fluid that exerts pressure on our bodies. At sea level, the value of atmospheric pressure is about 1.013 × 10⁵ Pa. This value is referred to as standard atmospheric pressure. It is an enormous pressure which can crush anything. We do not feel it because practically all bodies have air inside them. As atmospheric pressure acts in all directions, it balances the pressure inside.
lightbulbDo You Know? The pressure of 1 atmosphere is equivalent to placing a 1.0 kg mass (10 N weight) on an area of 1 cm².