What is the effect of increased humidity on air density?

Increased humidity has the effect of decreasing air density. This phenomenon can be attributed to the molecular composition of water vapor as compared to the other primary components of air, which are nitrogen (N₂) and oxygen (O₂).

When humidity rises, the amount of water vapor in the air increases. The molecular weight of water (approximately 18 g/mol) is less than that of nitrogen (approximately 28 g/mol) and oxygen (approximately 32 g/mol). As water vapor replaces these heavier gases, the overall average molecular weight of the air decreases, leading to a reduction in air density.

Understanding this concept is crucial for various applications in aerodynamics, meteorology, and aviation, as air density plays a significant role in lift generation, aircraft performance, and weather patterns.