FAA Ground School Practice Test

What processes contribute moisture to unsaturated air?

1. Condensation and precipitation

2. Evaporation and sublimination

3. Transpiration and respiration

4. Desorption and adsorption

The correct answer is: Evaporation and sublimination

The correct answer is evaporation and sublimation because both processes introduce moisture into the air, particularly in unsaturated conditions. Evaporation occurs when water from surfaces like lakes, rivers, and soil changes from liquid to vapor, thus adding moisture to the air. This is a common process that can significantly increase humidity, especially in warm conditions. Sublimation is the process where ice or snow directly changes into water vapor without first becoming liquid. This often happens in cold environments or at high altitudes, contributing moisture to the air as well. Together, these two processes are essential for increasing humidity levels in the atmosphere, particularly when the air is not fully saturated with moisture. Understanding these mechanisms is crucial in meteorology, as they impact weather patterns, cloud formation, and precipitation.