hydrological cycle (water cycle) The circulation of water between the atmosphere, land, and oceans on the earth. Water evaporates from the oceans and other water bodies on earth to form water vapour in the atmosphere. This may condense to form clouds and be returned to the earth's surface as precipitation (e.g. rainfall, hail, and snow). Some of this precipitation is returned to the atmosphere directly through evaporation or transpiration by plants; some flows off the land surface as overland flow, eventually to be returned to the oceans via rivers; and some infiltrates the ground to flow underground forming groundwater storage.

hydrological cycle (water cycle) Circulation of water around the Earth. Water evaporates from the sea; most falls back into the oceans, but cloud carries some over land. There it falls as precipitation, and by surface run off or infiltration and seepage, it gradually finds its way back to the sea. Less than 1% of the world's water is involved in this cycle.