American Meteorological Society Certification (AMS) Practice 2025 - Free Practice Questions and Study Guide

The process by which clouds form in the atmosphere is best described by condensation. This occurs when water vapor in the air cools and changes into liquid water droplets, which cluster together to create clouds. As air rises, it expands and cools, and if it cools to below its dew point, the water vapor condenses around tiny particles in the atmosphere, such as dust or salt, forming clouds.

Evaporation refers to the process of liquid water turning into vapor, which is the opposite of what happens during cloud formation. Adiabatic depressurization involves a change in pressure and temperature without heat exchange, but it is not directly related to the creation of clouds. Precipitation describes the process of water falling from clouds to the ground in the form of rain, snow, sleet, or hail, which occurs after cloud formation rather than during it. Thus, the most accurate term for the cloud formation process is condensation.