Biology STAAR (State of Texas Assessments of Academic Readiness) Practice Test

Cloud formation in the water cycle primarily occurs during the process of condensation. This process involves water vapor in the atmosphere cooling and changing from a gaseous state back into liquid water droplets. As water vapor rises and cools, it loses energy, leading to the formation of tiny water droplets or ice crystals, depending on the temperature. These droplets cluster together to form clouds.

While evaporation, transpiration, and precipitation are all important aspects of the water cycle, they do not directly lead to cloud formation. Evaporation transforms liquid water into vapor, adding moisture to the air but not creating clouds. Transpiration involves plants releasing water vapor into the atmosphere, which can contribute to humidity but does not directly result in cloud formation. Precipitation refers to the process of water falling from clouds (like rain or snow), which occurs after clouds have already formed. Therefore, condensation is the key process that directly results in the formation of clouds.