Chapter 6, Problem 1QFR

To determine

The reason why atmospheric pressure decreases with increasing altitude.

Answer to Problem 1QFR

Atmospheric pressure usually decreases with increasing height because of the compressible nature of Earth’s atmosphere and the number of air molecules will be lesser. In addition, the reduced influence of gravitational pull of Earth’s surface with height.

Explanation of Solution

Atmospheric pressure can be defined as the force exerted by the mass of gas molecules on a unit area of Earth's surface as well as on any other body on Earth. Atmospheric pressure is omnidirectional, meaning it exerts force equally in all directions (above, below, sides and diagonally).

Atmospheric pressure decreases with increasing altitude because the actual number of gas molecules is reduced. As we move farther away from Earth and its gravitational pull, the number of gas molecules present in the atmosphere will be lesser.

It decreases with height because of the compressible nature of the gas that is our atmosphere and the reduced effect of Earth’s gravitational pull with altitude. However, the rate of the pressure change is not uniform throughout the atmosphere. It changes rapidly at lower altitudes.