What does an increase in altitude typically do to air pressure?

An increase in altitude typically leads to a decrease in air pressure. This phenomenon occurs because as you ascend in the atmosphere, the weight of the air above you decreases. Air pressure is essentially the weight of the column of air above a given point; higher altitudes mean that there is less air above, resulting in lower pressure.

As altitude increases, the density of air molecules decreases, and consequently, the overall pressure exerted by these molecules diminishes. This principle is crucial for pilots and anyone involved in aviation, as it impacts aircraft performance, engine function, and the behavior of instruments that rely on atmospheric pressure. Understanding this relationship is vital for effective flight planning and operation in varying altitude conditions.