What effect does increased humidity have on aircraft performance?

Increased humidity has a discernible impact on aircraft performance, primarily leading to decreased engine output and reduced lift generated by the wings. When humidity levels rise, the density of the air decreases due to the presence of more water vapor, which replaces some of the heavier nitrogen and oxygen molecules in the air. This reduction in air density means that the aircraft's engines receive less oxygen for combustion, therefore potentially lowering engine power output.

Additionally, the lower density of humid air affects the lift produced by the wings. Aircraft rely on the density of the air to generate lift; a decrease in air density results in a decrease in lift at a given airspeed. As a result, an aircraft may require a longer runway for takeoff, as well as adjustments in climb performance. These effects underscore the importance of accounting for humidity levels during flight operations and performance calculations.