What impact does an increase in humidity have on density altitude?

An increase in humidity leads to an increase in density altitude because humidity affects the density of the air. When the air is more humid, it contains more water vapor which is less dense than the oxygen and nitrogen that comprise the bulk of the atmosphere. As a result, the overall density of the air decreases when humidity rises, which effectively raises the density altitude, even if the elevation above sea level remains unchanged.

Density altitude is a critical concept in aviation, particularly for understanding performance in flight. As density altitude increases, aircraft engines produce less power, propellers are less effective, and wings generate less lift, which can affect takeoff and landing performance. Understanding the relationship between humidity and density altitude is fundamental for pilots to ensure safe operations under varying atmospheric conditions.