Which factors affect air density?

Air density is influenced by several key factors, among which altitude, temperature, and humidity are primary contributors.

Altitude is significant because as altitude increases, air pressure decreases, leading to lower air density. This occurs because the weight of the air above diminishes as you move higher into the atmosphere, resulting in fewer air molecules in a given volume.

Temperature plays a critical role as well. Warmer air tends to expand, which means the same amount of air occupies a larger volume, thereby decreasing its density. Conversely, cooler air is denser since the molecules are more closely packed together.

Humidity affects air density because water vapor is less dense than the nitrogen and oxygen it replaces when moisture accumulates in the air. Thus, when humidity increases, the overall density of the air decreases since lighter water vapor displaces the heavier nitrogen and oxygen molecules.

Though other factors such as pressure are also relevant in determining air density, the combination of altitude, temperature, and humidity provides a comprehensive understanding of how these elements interact to influence air density in the atmosphere.