In oceanography, a halocline (from Greek hals, halos 'salt' and klinein 'to slope') is a cline, a subtype of chemocline caused by a strong, vertical salinitygradient within a body of water.[1] Because salinity (in concert with temperature) affects the density of seawater, it can play a role in its vertical stratification. Increasing salinity by one kg/m3 results in an increase of seawater density of around 0.7 kg/m3.
Halocline visible at the cenote Chac Mool, Mexico. The freshwater lies above the denser saltwater. In this photo, the visible water distortion from the halocline can be seen below the diver.
In the midlatitudes, an excess of evaporation over precipitation leads to surface waters being saltier than deep waters. In such regions, the vertical stratification is due to surface waters being warmer than deep waters and the halocline is destabilizing. Such regions may be prone to salt fingering, a process which results in the preferential mixing of salinity.
In certain high latitude regions (such as the Arctic Ocean, Bering Sea, and the Southern Ocean) the surface waters are actually colder than the deep waters and the halocline is responsible for maintaining water column stability, isolating the surface waters from the deep waters. In these regions, the halocline is important in allowing for the formation of sea ice, and limiting the escape of carbon dioxide to the atmosphere.
Haloclines are also found in fjords, and poorly mixed estuaries where fresh water is deposited at the ocean surface.[2]
A halocline can be easily created and observed in a drinking glass or other clear vessel. If fresh water is slowly poured over a quantity of salt water, using a spoon held horizontally at water-level to prevent mixing, a hazy interface layer, the halocline, will soon be visible due to the varying index of refraction across the boundary.
A halocline is most commonly confused with a thermocline – a thermocline is an area within a body of water that marks a drastic change in temperature. A halocline can coincide with a thermocline and form a pycnocline.[3]
Haloclines are common in water-filled limestone caves near the ocean. Less dense fresh water from the land forms a layer over salt water from the ocean.[1] For underwater cave explorers, this can cause the optical illusion of air space in caverns. Passing through the halocline tends to stir up the layers.
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Plot of temperature and salinity in the Arctic Ocean at 85,18 north and 117,28 east dated Jan. 1st 2010.[4]
In the graphical representation, three layers can be discerned:
About 50 m (160 ft) of low salinity water "swimming" on top of the ocean. The temperature is −1.8 °C (28.8 °F), which is very near to the freezing point. This layer blocks heat transfer from the warmer, deeper levels into the sea ice, which has considerable effect on its thickness.
About 150 m (490 ft) of steeply rising salinity and increasing temperature. This is the actual halocline.
The deep layer with nearly constant salinity and slowly decreasing temperature.[4]
^ abWhite, William B; Culver, David C (2012). Encyclopedia of Caves. Academic Press. p. 157. ISBN978-0-12-383832-2.
^Svensson, Torbjörn (6 February 1981). "Water Exchange and Mixing in Fjords" (PDF). www.chalmers.se. Chalmers University of Technology. p. 159. Retrieved 13 July 2020.
^Garrison, Tom (2006). Enhanced Essentials of Oceanography. Cengage Learning. p. 115. ISBN0-495-11372-7.
^ ab"U.S. National Oceanographic Data Center: Global Temperature–Salinity Profile Programme. June 2006. U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Oceanographic Data Center, Silver Spring, Maryland, 20910". 25 November 2020.
January 01, 1970
halocline, this, article, needs, additional, citations, verification, please, help, improve, this, article, adding, citations, reliable, sources, unsourced, material, challenged, removed, find, sources, news, newspapers, books, scholar, jstor, february, 2009, . This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Halocline news newspapers books scholar JSTOR February 2009 Learn how and when to remove this message In oceanography a halocline from Greek hals halos salt and klinein to slope is a cline a subtype of chemocline caused by a strong vertical salinity gradient within a body of water 1 Because salinity in concert with temperature affects the density of seawater it can play a role in its vertical stratification Increasing salinity by one kg m3 results in an increase of seawater density of around 0 7 kg m3 Contents 1 Description 1 1 Graph 2 Other types of clines 3 See also 4 ReferencesDescription edit nbsp Halocline visible at the cenote Chac Mool Mexico The freshwater lies above the denser saltwater In this photo the visible water distortion from the halocline can be seen below the diver In the midlatitudes an excess of evaporation over precipitation leads to surface waters being saltier than deep waters In such regions the vertical stratification is due to surface waters being warmer than deep waters and the halocline is destabilizing Such regions may be prone to salt fingering a process which results in the preferential mixing of salinity In certain high latitude regions such as the Arctic Ocean Bering Sea and the Southern Ocean the surface waters are actually colder than the deep waters and the halocline is responsible for maintaining water column stability isolating the surface waters from the deep waters In these regions the halocline is important in allowing for the formation of sea ice and limiting the escape of carbon dioxide to the atmosphere Haloclines are also found in fjords and poorly mixed estuaries where fresh water is deposited at the ocean surface 2 A halocline can be easily created and observed in a drinking glass or other clear vessel If fresh water is slowly poured over a quantity of salt water using a spoon held horizontally at water level to prevent mixing a hazy interface layer the halocline will soon be visible due to the varying index of refraction across the boundary A halocline is most commonly confused with a thermocline a thermocline is an area within a body of water that marks a drastic change in temperature A halocline can coincide with a thermocline and form a pycnocline 3 Haloclines are common in water filled limestone caves near the ocean Less dense fresh water from the land forms a layer over salt water from the ocean 1 For underwater cave explorers this can cause the optical illusion of air space in caverns Passing through the halocline tends to stir up the layers Graph edit nbsp Plot of temperature and salinity in the Arctic Ocean at 85 18 north and 117 28 east dated Jan 1st 2010 4 In the graphical representation three layers can be discerned About 50 m 160 ft of low salinity water swimming on top of the ocean The temperature is 1 8 C 28 8 F which is very near to the freezing point This layer blocks heat transfer from the warmer deeper levels into the sea ice which has considerable effect on its thickness About 150 m 490 ft of steeply rising salinity and increasing temperature This is the actual halocline The deep layer with nearly constant salinity and slowly decreasing temperature 4 Other types of clines editThermocline A cline based on difference in water temperature Chemocline A cline based on difference in water chemistry Pycnocline A cline based on difference in water density See also edit nbsp Underwater diving portal Hypersaline lake Landlocked body of water that contains concentrations of salts greater than the sea Isopycnal Line connecting points of a specific density or potential density Osmotic power Energy available from the difference in the salt concentration between seawater and river water Thermohaline circulation Part of large scale ocean circulation Thin layers oceanography References edit a b White William B Culver David C 2012 Encyclopedia of Caves Academic Press p 157 ISBN 978 0 12 383832 2 Svensson Torbjorn 6 February 1981 Water Exchange and Mixing in Fjords PDF www chalmers se Chalmers University of Technology p 159 Retrieved 13 July 2020 Garrison Tom 2006 Enhanced Essentials of Oceanography Cengage Learning p 115 ISBN 0 495 11372 7 a b U S National Oceanographic Data Center Global Temperature Salinity Profile Programme June 2006 U S Department of Commerce National Oceanic and Atmospheric Administration National Oceanographic Data Center Silver Spring Maryland 20910 25 November 2020 Retrieved from https en wikipedia org w index php title Halocline amp oldid 1196527135, wikipedia, wiki, book, books, library,
