Runoff Runoff Runoff is the one part of the water cycle. The water cycle describes how water goes from the air to the land and back to the air. To do this, water sometimes is in liquid form, other times it is water vapor.
Water can flow over the land in streams and rivers.
Other times it flows underground through soil and rocks. As water moves from one location to another and changes from vapor to liquid, scientists describe what happens as different processes . The water cycle has five main processes. Precipitation can take the forms of rain, snow, sleet, or hail. Precipitation occurs when areas of high pressure and low pressure air meet, or when areas of hot and cold air meet.