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post in: Facts, News Date:07 Jan 2013, 22:08 views:4613
An ocean is a body of saline water that composes much of a planet's hydrosphere.2 On Earth, an ocean is one of the major conventional divisions of the World shorts Ocean, which covers almost 71 of its surface. These are, in descending order by area, the Pacific, Atlantic, Indian, Southern (Antarctic and Arctic Oceans.34 The word sea is often used interchangeably with "ocean" in American English but, strictly speaking, a sea is a body of saline water (generally a division of the world.
Saline water covers approximately 72 of the planet's surface (3.6?108 km2) and is customarily divided into several principal oceans and smaller seas, with the ocean covering approximately 71 of Earth's surface and 90 of the Earth's biosphere.6 The ocean contains 97 of Earth's water, and.
Extraterrestrial oceans may be composed of water or other elements and compounds. The only confirmed large stable bodies of extraterrestrial surface liquids are the lakes of Titan, although there is evidence for the existence of oceans elsewhere in the Solar System. Early in their geologic histories, Mars and Venus are theorized to have had large water oceans.
The Mars ocean hypothesis suggests that nearly a third of the surface of Mars was once covered by water, and a runaway greenhouse effect may have boiled away the global ocean of Venus. Compounds such as salts and ammonia dissolved in water lower its freezing point so that water might exist in large quantities in extraterrestrial environments as brine or convecting ice. Unconfirmed oceans are speculated beneath the surface of many dwarf planets and natural satellites; notably, the ocean of Europa is estimated to have over sight twice the water volume of Earth.
The Solar System's giant planets are also thought to have liquid atmospheric layers of yet to be confirmed compositions. Oceans may also exist on exoplanets and exomoons, including surface oceans of liquid water within a circumstellar habitable zone. Ocean planets are a hypothetical type of planet with a surface completely covered with liquid.
The total mass of the hydrosphere is about.4 quintillion metric tons (1.4?1018 long tons.5?1018 short tons which is about.023 of Earth's total mass. Less than 3 is freshwater; the rest is saltwater, almost all of which is in the ocean. The area of the World Ocean is about 361.9 million square kilometers (139.7 million square miles 9 which covers about.9 of Earth's surface, and its volume is approximately.335 floor billion cubic kilometers (320.3 million cubic miles).9 This can be thought of as a cube.
Its average depth is about 3,688 meters (12,100 ft 9 and its maximum depth is 10,994 meters (6.831 mi) at the Mariana Trench.28 Nearly half of the world's marine waters are over 3,000 meters (9,800 ft) deep.15 The vast expanses of deep ocean (anything below. If a zone undergoes dramatic changes in temperature with depth, it contains a thermocline. The tropical thermocline is typically deeper than the thermocline at higher latitudes.
Polar waters, which receive relatively little solar energy, are not stratified by temperature and generally lack a thermocline because surface water at polar latitudes are nearly as cold as water at greater depths.