What effect does higher altitude have on air density?

At higher altitudes, the air density decreases. This phenomenon occurs because air pressure diminishes as altitude increases. The atmosphere is composed of layers, and as you ascend, there are fewer air molecules in a given volume, leading to lower density. This decrease in density affects various flight characteristics, including lift and engine performance, as the aircraft operates in air that is less dense than at lower elevations. Consequently, an aircraft requires higher true airspeed to achieve the same lift at increased altitudes because there are fewer air molecules available to create the necessary lift under the wings. Understanding this relationship is crucial for pilots and aviation professionals when planning flights and managing aircraft performance.