What effect does high humidity have on aircraft performance?

High humidity negatively impacts aircraft performance because it affects air density. When humidity levels are high, the water vapor in the air replaces oxygen molecules, reducing the overall density of the air. This results in decreased lift generated by the wings, reduced engine performance due to less oxygen for combustion, and diminished propeller efficiency.

As a result, pilots may notice that under high humidity conditions, their aircraft requires a longer takeoff distance, experiences a lower climb rate, and may handle differently than under drier conditions. Understanding the effects of humidity is crucial for pilots to make informed decisions regarding takeoff and landing performance, especially in varying weather conditions.