Question

What is Atmospheric pressure?
OR
Is Atmospheric pressure the same on every place on the surface of the Earth?

Answer 1

Air has weight and, therefore, the atmosphere exerts pressure on the surface of the earth. It has been calculated that at sea level the pressure of air is about 1kg per square centimetre or enough to support a column of mercury 76 cm. in a tube. But with increase of height above sea level the pressure decreases because the overlying column of air goes on getting shorter.