Precipitation and the Water Cycle

The air is full of water, even if you can't see it. Higher in the sky where it is colder than at the land surface, invisible water vapor condenses into tiny liquid water droplets—clouds. When the cloud droplets combine to form heavier cloud drops which can no longer "float" in the surrounding air, it can start to rain, snow, and hail... all forms of precipitation, the superhighway moving water from the sky to the Earth's surface. Note: This section of the Water Science School discusses the Earth's "natural" water cycle without human interference.