What three factors contribute to density altitude?

The correct choice highlights three crucial environmental factors that influence density altitude: humidity, altitude, and temperature.

Density altitude is a measure of air density and is effectively the altitude at which the air density corresponds to the standard atmospheric pressure at sea level (29.92 inches of Mercury) at a given temperature.

Temperature plays a significant role because warmer air is less dense than cooler air; as temperature increases, density altitude rises. Likewise, humidity impacts density; moist air is less dense than dry air at the same temperature, thus, an increase in humidity raises the density altitude. Finally, altitude itself is a factor because as one ascends in elevation, the atmospheric pressure decreases, leading to a decrease in air density, which results in a higher density altitude.

Collectively, these three factors—humidity, altitude, and temperature—interact to affect how aircraft perform in terms of lift, engine efficiency, and overall performance, making it vital for pilots and aircrews to understand their implications in aviation operations.