Commercial Pilot License (CPL) 2025 – 400 Free Practice Questions to Pass the Exam

Relative humidity measures the amount of water vapor in the atmosphere as a percentage of the total air capacity at a given temperature. This concept is crucial in meteorology and aviation because it helps to understand how much moisture the air can actually hold, which is temperature dependent.

As the air temperature rises, its capacity to hold water vapor also increases; conversely, cooler air can hold less moisture. Therefore, relative humidity is not just about the actual amount of water present; instead, it provides context regarding how close the air is to being saturated with moisture.

This measurement is key for pilots, as high relative humidity can affect aircraft performance, weather conditions, and the likelihood of fog or precipitation, making it essential for flight planning and safety. The other options refer to different aspects of humidity or water content, but do not specifically convey the relationship between the current water vapor present and the maximum capacity of the air at a given temperature.