Final answer:
Clouds are formed by the condensation of water vapor in the atmosphere as it cools, which leads to the formation of tiny droplets that accumulate into clouds and eventually fall as precipitation, contributing to the water cycle.
Step-by-step explanation:
Clouds form because water vapor condenses when rising air currents carry the vapor into the atmosphere where it cools. Condensation is the physical process by which atoms or molecules in the vapor phase enter the denser liquid phase. This occurs when gaseous water vapor cools sufficiently, allowing attractions between H₂O molecules to hold them together, creating tiny droplets of liquid water. These water droplets can accumulate to form clouds, and when they grow large enough, they fall as various forms of precipitation such as rain, snow, sleet, hail, or freezing rain. Most precipitation falls into the ocean, completing a segment of the water cycle.