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

• A. An increase in ambient pressure
• B. An increase in ambient temperature
• C. A decrease in humidity
• D. A decrease in altitude

Answer: (A)

Density altitude is the altitude in the standard atmosphere that would have the same air density as the air you’re currently experiencing. Air density decreases when the air is hotter, when the pressure is lower, or when the air is more humid. Because density altitude rises whenever the air becomes less dense, a rise in ambient temperature makes the air thinner and pushes the density altitude higher.

Increasing ambient pressure would make the air denser, which lowers density altitude. Decreasing humidity makes the air denser as well, also lowering density altitude. Decreasing altitude increases air density, again lowering density altitude. So the factor that would tend to increase density altitude is the ambient temperature rising.