Atmospheric pressure is the force per unit area exerted against a surface by the weight of air particles in Earth's atmosphere.
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Units of atmospheric pressure:
1 atm = 105 Pa
105 Pa = 105 N m-2
Barometer mercury gives atmospheric pressure to 76 cm Hg
Vertical column of water gives atmospheric pressure to 10.3 m.
- Atmospheric pressure depends on the height of a place above sea level and decreases with altitude. At higher altitude, the density and temperature of the air are lower, so the number of collisions between molecules are less and the pressure is lower.
- Atmospheric pressure can be measured by using barometer mercury, barometer Aneroid and barometer Fortin