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 ocean) partly or fully enclosed by land.5 Saline water covers approximately 72. If a zone undergoes a strong, vertical chemistry gradient with depth, it contains a chemocline. This acceleration of the current takes place in the direction of waves and dominant wind. Accordingly, when the sea depth increases, the rotation of the earth changes the direction of currents, in proportion with the increase of depth while friction lowers their. Below the thermocline, water is very cold, ranging from?1 C to 3 C. Because this deep and cold layer contains the bulk of ocean water, the average temperature of the world ocean is 3.9 tation needed If a zone undergoes dramatic changes in salinity with depth, it contains a halocline.
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.