What are you measuring when you measure air pressure?

Question

What are you measuring when you measure air pressure?

Answer 1

You are measuring the pressure difference between a vacuum and the atmosphere. Generally around 14.7 psi

Answer 2

Pounds per square inch.

Answer 3

All matter has mass. Any mass on or near the Earrth is attracted by Earth's gravitaty. The air, even though it has small mass, is also attracted to the Earth by gravity. If it were not attracted to the Earth, it would be lost into space.

Air pressure is a measurement of the weight of all of the air above us in the atmosphere. Technically, pressure is a force per unit area. Pounds per square inch are one set of units used to describe pressure. Our atmospheric pressure at sea level is about 14.7 pounds per square inch. This means that for each square inch of surface area, the air above it has a weight of 14.7 pounds.