Pressure On Land

Atmospheric Pressure

The weight of the air above us exerts pressure, and this is called atmospheric pressure.

Exactly how much pressure is exerted on us depends on altitude. Pressure is lowest at high altitudes because there is less air above you. And at lower altitudes, there is more air above you, so pressure increases.

In the United States, we use pounds per square inch (psi) to measure pressure. PSI refers to the amount of pressure exerted on 1 square inch of a surface.

Atmospheric pressure is equal to the weight of a 1 square inch column of air extending all the way to the edge of the earth's atmosphere. At sea level, this column weighs 14.7 pounds, so the atmospheric pressure is 14.7 psi. To make calculations easier, a unit of measurement called "atmospheres" or "ata" is used. 1 atmosphere of pressure is equal to 14.7 psi.

Exactly how much pressure is exerted on us depends on altitude. Pressure is lowest at high altitudes because there is less air above you. And at lower altitudes, there is more air above you, so pressure increases.

In the United States, we use pounds per square inch (psi) to measure pressure. PSI refers to the amount of pressure exerted on 1 square inch of a surface.

Atmospheric pressure is equal to the weight of a 1 square inch column of air extending all the way to the edge of the earth's atmosphere. At sea level, this column weighs 14.7 pounds, so the atmospheric pressure is 14.7 psi. To make calculations easier, a unit of measurement called "atmospheres" or "ata" is used. 1 atmosphere of pressure is equal to 14.7 psi.