Private Pilot Private Exam

The capacity of air to hold water vapor primarily depends on which factor?

1. Humidity

2. Air pressure

3. Air temperature

4. Wind speed

The correct answer is: Air temperature

The capacity of air to hold water vapor is primarily dependent on air temperature. As temperature increases, the air's ability to hold moisture also increases due to the greater kinetic energy of water molecules, which allows more water vapor to enter a gaseous state without condensing. Warm air can hold significantly more water vapor than cold air, which is why you often observe higher humidity levels during warm weather. Humidity itself is a measurement of how much water vapor is actually present in the air compared to the maximum amount the air can hold at a given temperature, but it does not directly determine that capacity. Air pressure does influence various atmospheric conditions, but it does not directly impact how much water vapor air can hold. Wind speed can affect local weather conditions and moisture distribution, but it does not determine the fundamental relationship between air temperature and moisture holding capacity.