Oceans are large depressions or basins on the surface of earth containing saline water and covers 71% of the earth’s surface and about 97% of earth’s water. Some of the major oceans of the world are, Pacific Ocean, Atlantic Ocean, Indian ocean, Arctic Ocean and Southern Ocean or Antarctic Ocean.
Water is an essential component of all life forms that exist over the surface of earth. Water is a rare commodity in our solar system. The earth fortunately has an abundant supply of water on its surface. Hence, our planet is called the ‘Blue Planet’.
Water cycle, also called hydrological cycle, involves the continuous circulation of water in the Earth – atmosphere system. Of the many processes involved in the water cycle, the most important are evaporation, transpiration, condensation, precipitation, and runoff.
WATER OF EARTH’S SURFACE
|Reservoir||Volume (Million Cubic km)||Percentage of the Total|
|Ice Caps and Glaciers||29||2.05|
|Streams and Rivers||0.0017||0.0001|
COMPONENTS AND PROCESSES OF THE WATER CYCLE
|Water storage in oceans||Evaporation, Evapotranspiration, Sublimation|
|Water in the atmosphere||Condensation, Precipitation|
|Water storage in ice and snow||Snowmelt runoff to streams|
|Surface runoff||Stream flow, freshwater storage, infiltration|
|Groundwater storage||Groundwater discharge springs|