The hydrosphere is often called the "water sphere" as it includes all the earth’s water that is found in oceans, seas, streams, lakes, soil, groundwater, and in the air.
The hydrosphere interacts with, and is influenced by, all the other four earth spheres including the cryosphere. Water is found in vapor, liquid and solid states phases in the atmosphere. The hydrologic cycle traces the movement of water and energy between these various stores and spheres.
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The World Health Organisation estimates that 80% of all sickness and diseases are due to inadequate water supplies and poor sanitation. The earth has all the water it needs to supply its 6.3 billion inhabitants with clean water. The problem is that water is not evenly distributed.
Ninety seven percent is salty and can be found in oceans. The remainder, a 2.5%, is freshwater, accessible from rivers, lakes, and reservoirs and locked in the ice caps of Antarctica and Greenland, and as (...)