Which factor would tend to increase the density altitude at a given airport?

Increasing the ambient temperature is a key factor that raises the density altitude at a given airport. Density altitude is an important concept in aviation that refers to the pressure altitude corrected for temperature. As temperature increases, the air becomes less dense, which means that the same volume of air contains fewer air molecules.

When the temperature rises, the air expands, leading to a decrease in density. This lower density means that an aircraft's performance is adversely affected, as there is less lift generated by the wings, reduced engine performance, and decreased propeller efficiency. Pilots must account for this in their flight planning, as a higher density altitude can significantly impact takeoff distance, climb rates, and overall performance.

Conversely, an increase in barometric pressure would actually decrease density altitude, as higher pressure allows for a denser air mass. Similarly, a decrease in relative humidity leads to drier air, which is also denser than more humid air, contributing to a lower density altitude. Therefore, increasing ambient temperature is the correct choice for factors that elevate density altitude at an airport.