Hydrologic cycle

The hydrologic cycle refers to the continuous motion of water between the ocean, land, and atmosphere. Water moves in the vapor phase from the oceans as evaporation and from the land as evaporation from the surface and by transpiration by plants to the atmosphere. (The combination of evaporation and transpiration is often termed evapotranspiration.) In the atmosphere, water condenses and forms clouds, which my transport water back to the surface as rain and snow. A portion of incoming precipitation is abosorbed by the land surface; the remainder runs off to be collected in streams and rivers. Ultimately, the liquid waters of the earth's surface is returned to the atmosphere and the cycle begins again.