Atmospheric Pressure Introduction
Our atmosphere is made up of an incredible number of molecules, bouncing around
from place to place. One cubic inch of air near sea level has about 4.4x1020
molecules in it! (That's around 440 billion billion molecules.) As these molecules
move around, they are constantly colliding with each other or anything else
that gets in the way - like us. The average force of all these collisions, per
unit area that they hit, is called air pressure. Since the molecules
move randomly in all directions, the air pressure at a given location is the
same in every direction. At sea level, the weight of the air produces a force
of about 14.7 pounds on every square inch of surface.
Go to the atmosphere.