Fundamentals of Refrigeration: Atmospheric Pressure

Because the air that fills our atmosphere has a weight, it also exerts pressure over the surface of the Earth. This pressure is referred to as “atmospheric pressure”, “air pressure”, or “barometric pressure”. At sea level, experiments have proven that the atmospheric pressure is 14.696 psi.

Since the density of air decreases as the elevation increases, the atmospheric pressure also decreases. This means that the atmospheric pressure at a Colorado Rockies home baseball game is approximately 20% less than at a game played at sea level. In a baseball context, this reduces the air resistance on a baseball, allowing a hit ball to travel further.

For most refrigeration applications, however, atmospheric pressure is approximated as 14.7 psi.