What does an increase in altitude generally do to atmospheric pressure?

An increase in altitude generally leads to a decrease in atmospheric pressure. This occurs because the atmosphere consists of layers of air, and as you ascend, there is less air above you pressing down due to gravity. The weight of the air column decreases, resulting in lower pressure.

As altitude increases, there are fewer air molecules in a given volume, leading to a lower density of air. This reduction in density translates to a decrease in the total atmospheric pressure experienced at higher elevations. This principle is crucial for understanding aircraft performance, weather patterns, and human physiology at different altitudes.