Atmospheric pressure is the force per unit area exerted by t
Atmospheric pressure is the force per unit area exerted by the weight of the air in Earth’s atmosphere on any surface.
In simple terms, the air around us has weight. The enormous column of air above your head presses down on everything, creating atmospheric pressure.
P=F/A
Key facts
* Average pressure at sea level: 101,325 pascals (Pa), or 1 atmosphere (1 atm).
* Unit: Pressure is commonly measured in pascals (Pa), kilopascals (kPa), atmospheres (atm), millimeters of mercury (mmHg), or pounds per square inch (psi).
* Instrument used: A barometer measures atmospheric pressure.
* Effect of altitude: Atmospheric pressure decreases as you go higher because there is less air above you.
Everyday examples
* Drinking through a straw works because atmospheric pressure pushes the liquid up the straw.
* Weather changes are linked to changes in atmospheric pressure:
* High pressure usually brings clear, stable weather.
* Low pressure is often associated with clouds, wind, and rain.
* Water boils at a lower temperature on high mountains because the atmospheric pressure is lower.
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