THE WATER CYCLE
   Biological importance: Water is essential to all organisms.

   Forms  available  to  life: Liquid water is the primary phase in which
   water is used, though some organisms can harvest water vapor.

   Reservoirs:  The  oceans  contain  97$  of the water in the biosphere.
   About 2$ is bound in glaciers and polar ice caps, and the remaining 1%
   is in lakes, rivers, and ground water.

   Key  processes:  The  main  processes are evaporation of liquid water,
   condensation  into  clouds, and precipitation. Transpiration by plants
   also moves significant volumes of water. Surface and groundnwater flow
   can return water to the oceans.