How does the density of air change as altitude increases?

As altitude increases, the density of air decreases. This occurs because as you move higher into the atmosphere, the pressure exerted by the weight of the air above you diminishes. Since air is made up of molecules that occupy a certain amount of space, when the atmosphere is less compressed (which happens at higher altitudes), the same volume of air contains fewer molecules. This results in a lower density.

The relationship between altitude and air density is critical for various applications, including aviation, where understanding how thinner air affects lift and engine performance is important. This decreasing trend continues as you ascend until you reach the stratosphere, where density remains low. Therefore, the understanding that air density decreases with increasing altitude is pivotal in fields that study atmospheric behavior.