The atmosphere is held on the earth by the gravitational pull of the earth. A column of air exerts weight in terms of pressure on the surface of the earth. The weight of the column of air at a given place and time is called air pressure or atmospheric pressure. Atmospheric pressure is measured by an instrument called barometer. Now a days Fortin’s barometer and Aneroid barometer I are commonly used for measuring air pressure. Grade : 7 Subject : Geography Lesson :Air Topic:Atmospheric Pressure Useful for CBSE, ICSE, NCERT & International Students