The hydrosphere (from Greek ὕδωρ - hudōr, "water"[1] and σφαῖρα - sphaira, "sphere"[2]) in physical geography describes the combined mass of water found on, under, and over the surface of a planet.
The total mass of the Earth's hydrosphere is about 1.4 × 1018 tonnes, which is about 0.023% of the Earth's total mass. About 20 × 1012 tonnes of this is in the Earth's atmosphere (the volume of one tonne of water is approximately 1 cubic metre). Approximately 75% of the Earth's surface, an area of some 361 million square kilometers (139.5 million square miles), is covered by ocean. The average salinity of the Earth's oceans is about 35 grams of salt per kilogram of sea water (3.5%) [3]
[edit] Water cycle
Main article:
Water cycleEnergy from the sun, in the form of heat and light (insolation), causes evaporation from all wet surfaces including oceans, rivers, lakes, soil and the leaves of plants. Water vapor is further released as transpiration from vegetation and from humans and other animals.
[edit] See also
[edit] References
- ^ ὕδωρ, Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus
- ^ σφαῖρα, Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus
- ^ Kennish, Michael J. (2001). Practical handbook of marine science. Marine science series (3rd ed.). CRC Press. p. 35. ISBN 0-8493-2391-6.
[edit] External links
