The Water Cycle
Earth’s water is always moving. The water cycle describes this continuous movement of water on, above and below the surface of the Earth.
The water cycle has no beginning or end. Water can change states among liquid, vapor and ice at various places in the cycle. These processes happen in the blink of an eye and over millions of years. Although the balance of water on Earth remains fairly constant over time, individual water molecules can come and go in a hurry.