How does an increase in temperature typically affect density altitude?

An increase in temperature affects density altitude by increasing it. Density altitude is a measure of how high the altitude feels to an aircraft due to the density of the air, which is influenced by temperature, pressure, and humidity. As temperature rises, the air becomes less dense because warmer air expands and occupies a larger volume. This lower density of air means that for a given pressure altitude, the density altitude increases.

When density altitude is higher, the aircraft experiences reduced performance, including lower engine output, reduced propeller efficiency, and diminished lift generated by the wings. This is particularly crucial during takeoff and landing, as higher density altitudes can lead to longer takeoff distances and longer landing distances due to the aircraft needing more speed to achieve sufficient lift.

The other choices do not accurately describe the relationship between temperature and density altitude. For instance, an increase in temperature cannot decrease density altitude, as that goes against the basic principles of thermodynamics concerning air density. Similarly, it is incorrect to state that an increase in temperature has no effect or makes no difference to aircraft performance, since these factors are critical in flight operations. Understanding this relationship is fundamental for pilots to make informed decisions regarding flight safety and performance.