What effect does an increase in altitude have on air density?

As altitude increases, air density decreases. This phenomenon occurs because the atmosphere is composed of layers of air, and as you ascend, the weight of the air above you diminishes. Consequently, the pressure exerted by the air decreases, resulting in a lower concentration of air molecules per unit volume. In simpler terms, there are fewer air molecules at higher altitudes, which translates to reduced air density. This decrease in density has significant implications for aircraft performance, including lift generation and engine efficiency, as aircraft rely on denser air to produce lift and maintain combustion in their engines. Understanding this relationship is crucial for pilots and aviation professionals in making informed decisions regarding flight operations at various altitudes.