How does increasing altitude generally affect gas pressure?

Increasing altitude generally leads to a decrease in atmospheric pressure. This occurs because as one ascends in altitude, there is less air above pressing down due to gravity. The atmosphere is less dense at higher elevations since there are fewer air molecules in a given volume. As a result, the weight of the air column above decreases, leading to lower pressure at higher altitudes.

This principle is fundamental to understanding how gases behave in the atmosphere and how they are influenced by changes in altitude. In mountainous regions or during a flight, one can experience this decrease in pressure, which is why airplanes must be pressurized to ensure the safety and comfort of passengers and crew.