Final answer:
When water vapor in the air cools down and changes into water droplets, the process is known as condensation, which is a pivotal step in the water cycle leading to precipitation.
Step-by-step explanation:
When water lowers in temperature and allows water droplets to form, this is called condensation. Condensation is the process in which water vapor changes to liquid water, such as the droplets you see on the outside of a cold beverage glass or the formation of fog. This process is essential in the water cycle as it leads to the creation of clouds, and eventually, when the droplets combine and grow large enough, they fall to Earth as precipitation (rain, snow, sleet, hail).