"විල්" හි සංශෝධන අතර වෙනස්කම්

සබැඳි සංස්කරණය කරන්න
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සුළු Singhalawap විසින් යලියොමුවක් නොදමාම විල පිටුව විල් වෙත ගෙනයන ලදී
පිටුව වෙනුවට 'ගොඩබිමින් වටවූ ස්වභාවිකව විශාල මිරි...' ප්‍රතිස්ථාපනය කරමින්
1 පේළිය: 1 පේළිය:
ගොඩබිමින් වටවූ ස්වභාවිකව විශාල මිරිදිය ජලස්කන්ධයක් රැස්වන භූ අවපාතයන් '''විල්''' නම් වේ.
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[[ගොනුව:Bariloche-_Argentina2.jpg|thumb|220px|Lake Nahuel Huapi, Bariloche (Argentina).]]
[[ගොනුව:Mazandaransea02.jpg|thumb|220px|[[Caspian Sea]] in northen [[Iran]] is the largest lake in the world.]]
[[ගොනුව:Lake Tahoe NV.jpg|thumb|right|220px|[[Lake Tahoe]] on the border of [[California]] and [[Nevada]].]]
[[ගොනුව:Blowdown Lake Billy Chinook, Deschutes National Forest, Oregon (photo by Bob Nichol).jpg|thumb|right|220px|Blowdown Lake in the mountains near [[Pemberton, British Columbia]]]]

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A '''lake''' (from Latin ''lacus'') is a [[terrain feature]] (or [[physical feature]]), a body of [[liquid]] on the surface of a world that is localized to the bottom of [[basin]] (another type of landform or terrain feature; that is, it is not global) and moves slowly if it moves at all. On Earth, a body of water is considered a lake when it is inland, not part of the [[ocean]], is larger and deeper than a [[pond]], and is fed by a river.<ref
>{{cite web
|url=http://www.britannica.com/EBchecked/topic/328083/lake
|author=Brittanica online
|accessdate=2008-06-25
|title=Lake (physical feature)
|quote=[a Lake is] any relatively large body of slowly moving or standing water that occupies an inland basin of appreciable size. Definitions that precisely distinguish lakes, ponds, swamps, and even rivers and other bodies of nonoceanic water are not well established. It may be said, however, that rivers and streams are relatively fast moving; marshes and swamps contain relatively large quantities of grasses, trees, or shrubs; and ponds are relatively small in comparison to lakes. Geologically defined, lakes are temporary bodies of water.}}</ref
><ref>{{cite web

|title=Dictionary.com definition
|accessdate=2008-06-25
|url=http://dictionary.reference.com/browse/lake
a body of fresh or salt water of considerable size, surrounded by land.}}</ref> The only world other than Earth known to harbor lakes is [[Titan (moon)|Titan]], Saturn's largest moon, which has lakes of [[ethane]], most likely mixed with [[methane]]. It is not known if Titan's lakes are fed by rivers, though Titan's surface is carved by numerous river beds.

Natural lakes on Earth are generally found in mountainous areas, [[rift zone]]s, and areas with ongoing or recent [[glacier|glaciation]]. Other lakes are found in [[endorheic basin]]s or along the courses of mature rivers. In some parts of the world, there are many lakes because of chaotic drainage patterns left over from the last [[Ice Age]]. All lakes are temporary over geologic time scales, as they will slowly fill in with sediments or spill out of the basin containing them.

== Meaning and usage of "lake" ==

[[ගොනුව:Maracaibo MODIS 2004jun26.jpg|thumb|220px|[[Lake Maracaibo]] (technically a [[bay]]), [[Venezuela]]. Green swirls on the lake are duckweed.]]

There is considerable uncertainty about defining the difference between lakes and ponds. For example, limnologists have defined lakes as waterbodies which are simply a larger version of a pond or which have wave action on the shoreline, or where wind induced turbulence plays a major role in mixing the water column. None of these definitions completely excludes ponds and all are difficult to measure. For this reason there has been increasing use made of simple size-based definitions to separate ponds and lakes. In the United Kingdom, for example, the charity Pond Conservation - which works to protect all types of [[freshwater ecosystem]] - has defined lakes as waterbodies of {{convert|2|ha|0}} or more in area.<ref>Williams P, Whitfield M, Biggs J, Bray S, Fox G, Nicolet P and Sear D. (2004). Comparative biodiversity of rivers, streams, ditches and ponds in an agricultural landscape in Southern England. Biological Conservation 115: 329-341.</ref> Elsewhere, other workers have treated lakes as waterbodies of {{convert|5|ha}} and above, or {{convert|8|ha}} and above (see definitions of [[pond]]). Charles Elton, one of the founders of ecology, regarded lakes as waterbodies of {{convert|40|ha}} or more, a value somewhat larger than modern studies would suggest appropriate.<ref>Elton, C.S. and Miller, R.S. (1954). The ecological survey of animal communities: with a practical system of classifying habitats by structural characters. Journal of Ecology, 42, 460-496.</ref> The term "lake" is also used to describe a feature such as [[Lake Eyre]], which is a dry basin most of the time but may become filled under seasonal conditions of heavy rainfall.

Further, in common usage, many lakes bear names ending with the word "pond", and a lesser number of names ending with "lake" are in quasi-technical fact, ponds. In short, there is no current internationally accepted definition of either term across scientific disciplines or political boundaries. Within disciplines, authors are careful to define environmental geographic circumstances, and obviates the need for artificially imposed definitions when most of the worlds' people speak different languages.

In [[Lentic ecosystems|lake ecology]] the environment of a lake is referred to as ''lacustrine''. Large lakes are occasionally referred to as "inland [[sea]]s", and small seas are occasionally referred to as lakes. Smaller lakes tend to put the word "lake" after the name, as in [[Green Lake (Seattle)|Green Lake]], while larger lakes often invert the word order, as in [[Lake Ontario]], at least in North America. In some places, the word "lake" does not correctly appear in the name at all (e.g., [[Windermere (lake)|Windermere]] in [[Cumbria]]).

Only one lake in the English [[Lake District]] is actually called a lake; other than [[Bassenthwaite Lake]], the others are all "[[Mere (lake)|meres]]" or "waters". Only six bodies of water in [[ස්කොට්ලන්තය]] are known as lakes (the others are [[loch]]s): the [[Lake of Menteith]], the [[Lake of the Hirsel]], [[Pressmennan Lake]], Cally Lake near [[Gatehouse of Fleet]], the saltwater Manxman's Lake at [[Kirkcudbright]] Bay, and The Lake at Fochabers. Of these only the Lake of Menteith and Cally Lake are natural bodies of fresh water.

[[ගොනුව:Rila 7 lakes circus panorama edit1.jpg|right|thumb|220px|The [[Seven Rila Lakes]] are a group of glacial lakes in the [[Bulgaria]]n [[Rila]] mountains]]

[[ගොනුව:Oeschinen.jpg|thumb|right|220px|[[Oeschinen Lake]] in the [[Swiss Alps]]]]

== Distribution of lakes ==

The majority of lakes on Earth are [[fresh water]], and most lie in the [[Northern Hemisphere]] at higher [[latitude]]s. More than 60% of the world's lakes are in [[Canada]]; this is because of the [[Drainage system (Geomorphology)#Deranged drainage system|deranged drainage system]] that dominates the country.

[[Finland]] is known as ''The Land of the Thousand Lakes'', (actually there are 187,888 lakes in Finland, of which 60,000 are large),<ref>[http://www.stat.fi/index_en.html Statistics Finland]</ref> and the [[U.S.]] state of [[Minnesota]] is known as ''The Land of Ten Thousand Lakes''. The license plates of the [[Canadian]] province of [[Manitoba]] used to claim "100,000 lakes" as one-upmanship on [[Minnesota]], whose license plates boast of its "10,000 lakes."

Most lakes have a natural outflow in the form of a [[river]] or stream, but some do not and lose water solely by evaporation or underground seepage or both. They are termed [[endorheic]] lakes (see below).

Many lakes are artificial and are constructed for [[hydro-electric]] power generation, [[recreation]]al purposes, [[Industry|industrial]] use, [[agricultural]] use, or domestic water supply.

Evidence of extraterrestrial lakes exists; "definitive evidence of lakes filled with methane" was announced by NASA as returned by the [[Cassini–Huygens|Cassini Probe]] observing the moon [[Titan (moon)|Titan]], which orbits the planet [[Saturn]].

Globally, lakes are greatly outnumbered by ponds: of an estimated 304 million standing water bodies worldwide, 91% are {{convert|1|ha}} or less in area (see definition of [[pond]]s) <ref>Downing JA, Prairie YT, Cole JJ, Duarte CM, Tranvick LJ, Striegel RG, McDowell WH, Kortelainen P, Melack JM, Middleburg JJ (2006). The global abundance and size distribution of lakes, ponds and impoundments. Limnology and Oceanography, 51: 2388-2397.</ref>. Small lakes are also much more numerous than big lakes: in terms of area, one third of the world's standing water is represented by lakes and ponds of {{convert|10|ha}} or less. However, large lakes contribute disproportionately to the area of standing water with 122 large lakes of <!--{{convert|1000|km2}} (100,000 [[ha]], 247,000 acres)--->1,000 square kilometres (390 sq mi, 100,000 [[ha]], 247,000 [[acre]]s) or more representing about 29% of the total global area of standing inland water.

== Origin of natural lakes ==
[[ගොනුව:Lake-huron-ipperwash-beach.jpg|thumb|220px|[[Ipperwash Beach]], [[Lake Huron]], [[Ontario]], [[Canada]]]]

There are a number of natural processes that can form lakes. A recent [[tectonics|tectonic]] uplift of a mountain range can create bowl-shaped depressions that accumulate water and form lakes. The advance and retreat of glaciers can scrape depressions in the surface where water accumulates; such lakes are common in [[Scandinavia]], [[Patagonia]], [[Siberia]], and [[Canada]]. The most notables examples are probably the [[Great Lakes]] of [[North America]].

Lakes can also form by means of landslides or by glacial blockages. An example of the latter occurred during the last ice age in the U.S. state of [[Washington]], when a huge lake formed behind a glacial flow; when the ice retreated, the result was an immense flood that created the [[Dry Falls]] at [[Sun Lakes State Park|Sun Lakes]], [[Washington]].

[[salt lake (geography)|Salt lakes]] (also called [[saline]] lakes) can form where there is no natural outlet or where the water evaporates rapidly and the drainage surface of the [[water table]] has a higher-than-normal [[salt]] content. Examples of salt lakes include [[Great Salt Lake]], the [[Caspian Sea]], the [[Aral Sea]], and the [[Dead Sea]].

Small, crescent-shaped lakes called [[oxbow lake]]s can form in river valleys as a result of meandering. The slow-moving river forms a sinuous shape as the outer side of bends are eroded away more rapidly than the inner side. Eventually a horseshoe bend is formed and the river cuts through the narrow neck. This new passage then forms the main passage for the river and the ends of the bend become silted up, thus forming a bow-shaped lake.

[[Crater lake]]s are formed in [[volcanic crater]]s and [[caldera]]s which fill up with precipitation more rapidly than they empty via evaporation. Sometimes the latter are called caldera lakes, although often no distinction is made. An example is [[Crater Lake]] in [[Oregon]], located within the caldera of [[Mount Mazama]]. The caldera was created in a massive volcanic eruption that led to the subsidence of Mount Mazama around 4860 BC.

Some lakes, such as [[Lake Jackson (Tallahassee, Florida)|Lake Jackson]] in Florida, USA, come into existence as a result of [[sinkhole]] activity.

[[Lake Vostok]] is a [[subglacial lake]] in [[Antarctica]], possibly the largest in the world. The pressure from the ice atop it and its internal chemical composition mean that, if the lake were drilled into, a fissure could result that would spray somewhat like a [[geyser]].

Most lakes are geologically young and shrinking since the natural results of [[erosion]] will tend to wear away the sides and fill the basin. Exceptions are those such as [[Lake Baikal]] and [[Lake Tanganyika]] that lie along continental [[rift valley|rift zones]] and are created by the crust's [[subsidence]] as two plates are pulled apart. These lakes are the oldest and deepest in the world. [[Lake Baikal]], which is 25-30 million years old, is deepening at a faster rate than it is being filled by erosion and may be destined over millions of years to become attached to the [[global ocean]]. The [[Red Sea]], for example, is thought to have originated as a [[rift valley]] lake.

== Types of lakes ==
[[ගොනුව:Arizona-sunset.jpg|thumb|220px|right|One of the many artificial lakes in [[Arizona]] at sunset]]
* [[Periglacial]]: Part of the lake's margin is formed by an [[ice sheet]], [[ice cap]], or [[glacier]], the ice having obstructed the natural [[drainage]] of the land.
* [[Subglacial lake|Subglacial]]: A lake which is permanently covered by [[ice]]. They can occur under glaciers, ice caps, or ice sheets. There are many such lakes, but [[Lake Vostok]] in [[Antarctica]] is by far the largest. They are kept [[liquid]] because the overlying ice acts as a [[thermal insulator]] retaining energy introduced to its underside by [[friction]], by water percolating through crevasses, by the pressure from the [[mass]] of the ice sheet above, or by [[geothermal heating]] below.
* [[Glacial lake]]: a lake with origins in a melted glacier.
* [[Artificial lake]]: A lake created by [[flood]]ing land behind a [[dam]], called an impoundment or [[Reservoir (water)|reservoir]]; by deliberate human excavation; or by the flooding of an excavation incident to a mineral-extraction operation such as an [[open-pit mining|open pit mine]] or [[quarry]]. Some of the world's largest lakes are reservoirs.
[[ගොනුව:Kuekenhoff Canal 002.jpg|220px|thumb|A man-made lake in [[Keukenhof]], [[Netherlands]]]]
* [[Endorheic basin|Endorheic]], terminal or closed: A lake which has no significant outflow, either through rivers or underground diffusion. Any water within an endorheic basin leaves the system only through [[evaporation]] or [[Seepage#Permeability and seepage|seepage]]. These lakes, such as [[Lake Eyre]] in central [[ඕස්ට්‍රේලියාව]] or the [[Aral Sea]] in central Asia, are most common in desert locations.
* [[Meromictic]]: A lake which has layers of water which do not intermix. The deepest layer of water in such a lake does not contain any dissolved oxygen. The layers of sediment at the bottom of a meromictic lake remain relatively undisturbed because there are no living [[aerobic organisms]].
* [[Fjord|Fjord lake]]: A lake in a glacially eroded valley that has been eroded below sea level.
* [[Oxbow lake|Oxbow]]: A lake which is formed when a wide meander from a stream or a river is cut off to form a lake. They are called "oxbow" lakes due to the distinctive curved shape that results from this process.
* [[Rift lake]] or [[sag pond]]: A lake which forms as a result of subsidence along a geological fault in the Earth's [[tectonic plate]]s. Examples include the [[Rift Valley lakes]] of eastern [[Africa]] and [[Lake Baikal]] in [[Siberia]].
* [[Underground lake|Underground]]: A lake which is formed under the surface of the Earth's crust. Such a lake may be associated with [[caves]], [[aquifer]]s, or [[spring (hydrosphere)|springs]].

[[ගොනුව:DirkvdM irazu 4.jpg|220px|thumb|The crater lake of [[Volcán Irazú]], [[Costa Rica]]]]
* [[Crater lake|Crater]]: A lake which forms in a volcanic [[caldera]] or crater after the volcano has been inactive for some time. Water in this type of lake may be [[fresh water|fresh]] or highly [[acidic]] and may contain various dissolved [[mineral water|minerals]]. Some also have [[Geothermal (geology)|geothermal]] activity, especially if the volcano is merely dormant rather than extinct.
* [[Lava lake|Lava]]: A pool of molten lava contained in a volcanic crater or other depression. Lava lakes that have partly or completely solidified are also referred to as lava lakes.
* [[:Category:Former lakes|Former]]: A lake which is no longer in existence. Such lakes include [[prehistoric]] lakes and lakes which have permanently dried up through [[evaporation]] or human intervention. [[Owens Lake]] in [[California]], USA, is an example of a former lake. Former lakes are a common feature of the [[Basin and Range]] area of southwestern North America.
* Seasonal lake: A lake that exists as a [[Bodies of water|body of water]] during only part of the year.
* [[:Category:Shrunken lakes|Shrunken]]: Closely related to ''former'' lakes, a shrunken lake is one which has drastically decreased in size over geological time. [[Lake Agassiz]], which once covered much of central North America, is a good example of a shrunken lake. Two notable remnants of this lake are [[Lake Winnipeg]] and [[Lake Winnipegosis]].
* [[Eolic]]: A lake which forms in a depression created by the activity of the [[winds]].

== Characteristics ==
[[ගොනුව:Lake mapourika NZ.jpeg|220px|thumb|[[Lake Mapourika]], [[නවසීලන්තය]]]]
Lakes have numerous features in addition to lake type, such as [[drainage basin]] (also known as catchment area), inflow and outflow, [[nutrient]] content, [[dissolved oxygen]], [[water pollution|pollutants]], [[pH]], and [[sediment]]ation.

Changes in the level of a lake are controlled by the difference between the input and output compared to the total volume of the lake. Significant input sources are precipitation onto the lake, runoff carried by streams and channels from the lake's [[drainage basin|catchment]] area, [[groundwater]] channels and aquifers, and artificial sources from outside the catchment area. Output sources are evaporation from the lake, surface and groundwater flows, and any extraction of lake water by humans. As climate conditions and human water requirements vary, these will create fluctuations in the lake level.

Lakes can be also categorized on the basis of their richness in nutrients, which typically affects plant growth. Nutrient-poor lakes are said to be ''[[oligotroph]]ic'' and are generally clear, having a low concentration of plant life. ''[[Mesotrophic lake]]s'' have good clarity and an average level of nutrients. ''[[Eutrophic]]'' lakes are enriched with nutrients, resulting in good plant growth and possible [[algal blooms]]. ''[[Hypertrophic]]'' lakes are bodies of water that have been excessively enriched with nutrients. These lakes typically have poor clarity and are subject to devastating algal blooms. Lakes typically reach this condition due to human activities, such as heavy use of fertilizers in the lake catchment area. Such lakes are of little use to humans and have a poor ecosystem due to decreased dissolved oxygen.

Due to the unusual relationship between [[water]]'s [[temperature]] and its [[density]], lakes form layers called [[thermocline]]s, layers of drastically varying temperature relative to depth. Fresh water is most dense at about 4 degrees [[Celsius]] (39.2&nbsp;°F) at sea level. When the temperature of the water at the surface of a lake reaches the same temperature as deeper water, as it does during the cooler months in [[temperate]] climates, the water in the lake can mix, bringing oxygen-starved water up from the depths and bringing oxygen down to decomposing sediments. Deep temperate lakes can maintain a reservoir of cold water year-round, which allows some cities to tap that reservoir for [[deep lake water cooling]].

[[ගොනුව:Yaylyu.JPG|thumb|220px|[[Lake Teletskoye]], [[Siberia]]]]
Since the surface water of deep [[tropical]] lakes never reaches the temperature of maximum density, there is no process that makes the water mix. The deeper layer becomes oxygen starved and can become saturated with carbon dioxide, or other gases such as sulfur dioxide if there is even a trace of [[volcano|volcanic activity]]. Exceptional events, such as earthquakes or landslides, can cause mixing, which rapidly brings up the deep layers and can release a vast cloud of toxic gases which lay trapped in solution in the colder water at the bottom of the lake. This is called a [[limnic eruption]]. An example of such a release is [[Lake Nyos#The 1986 disaster|the disaster at Lake Nyos]] in [[Cameroon]]. The amount of gas that can be dissolved in water is directly related to pressure. As the previously deep water surfaces, the pressure drops, and a vast amount of gas comes out of solution. Under these circumstances even carbon dioxide is toxic because it is heavier than air and displaces it, so it may flow down a river valley to human settlements and cause mass [[asphyxiation]].

The material at the bottom of a lake, or ''lake bed'', may be composed of a wide variety of [[inorganic]]s, such as [[silt]] or [[sand]], and [[organic material]], such as decaying plant or animal matter. The composition of the lake bed has a significant impact on the flora and fauna found within the lake's environs by contributing to the amounts and the types of nutrients available.

A paired (black and white) layer of the varved lake sediments correspond to a year. During winter, when organisms die, carbon is deposited down, resulting to a black layer. At the same year, during summer, only few organic materials are deposited, resulting to a white layer at the lake bed. These are commonly used to track paleontological events which happened in the past.

== Limnology ==
{{main article|Limnology|Lake ecosystem|Lake aeration}}
[[ගොනුව:Lake_Billy_Chinook,_Deschutes_National_Forest,_Oregon_(photo_by_Bob_Nichol).jpg|220px|thumb|[[Lake Billy Chinook]], Deschutes National Forest, [[Oregon]].]]
[[Limnology]] is the study of inland bodies of water and related ecosystems. Limnology divides lakes into three zones: the ''[[littoral zone]]'', a sloped area close to land; the ''[[photic zone|photic]]'' or ''open-water zone'', where sunlight is abundant; and the deep-water ''[[profundal zone|profundal]]'' or ''[[benthic zone]]'', where little sunlight can reach. The depth to which light can reach in lakes depends on [[turbidity]], determined by the density and size of suspended [[Particle (ecology)|particles]]. A particle is in [[Suspension (chemistry)|suspension]] if its weight is less than the random [[turbidity]] [[force]]s acting upon it. These particles can be [[sediment]]ary or [[Biotic material|biological]] in origin and are responsible for the color of the water. Decaying plant matter, for instance, may be responsible for a yellow or brown color, while algae may cause greenish water. In very shallow water bodies, iron oxides make water reddish brown. Biological particles include [[alga]]e and [[detritus]]. Bottom-dwelling detritivorous [[fish]] can be responsible for turbid waters, because they stir the mud in search of food. [[Piscivorous]] fish contribute to turbidity by eating plant-eating ([[plankton]]ivorous) fish, thus increasing the amount of algae (see aquatic [[trophic cascade]]). The light depth or transparency is measured by using a ''[[Secchi disk]]'', a 20-centimeter (8&nbsp;in) disk with alternating white and black [[quadrant]]s. The depth at which the disk is no longer visible is the ''Secchi depth'', a measure of transparency. The Secchi disk is commonly used to test for [[eutrophication]]. For a detailed look at these processes, see [[lentic ecosystems]].

A lake moderates the surrounding region's [[temperature]] and [[climate]] because [[water]] has a very high [[specific heat capacity]] (4,186 J·kg<sup>−1</sup>·K<sup>−1</sup>). In the daytime, a lake can cool the land beside it with local [[wind]]s, resulting in a [[sea breeze]]; in the night, it can warm it with a [[land breeze]].

== How lakes disappear ==
[[ගොනුව:ShrinkingLakeChad-1973-1997-EO.jpg|thumb|220px|[[Lake Chad]] in a 2001 satellite image, with the actual lake in blue, and vegetation on top of the old lake bed in green. Above that, the changes from 1973 to 1997 are shown.]]
A lake may be infilled with deposited sediment and gradually become a [[wetland]] such as a [[swamp]] or [[marsh]]. <!--Important differences exist between lowland and highland lakes: lowland lakes are more placid, are less rocky and more sedimentary, have a less sloping bottom, and generally contain more plant life than highland lakes.--> Large water plants, typically [[Phragmites|reeds]], accelerate this closing process significantly because they partially decompose to form peat soils that fill the shallows. Conversely, peat soils in a marsh can naturally burn and reverse this process to recreate a shallow lake. Turbid lakes and lakes with many plant-eating fish tend to disappear more slowly. A "disappearing" lake (barely noticeable on a human timescale) typically has extensive plant mats at the water's edge. These become a new habitat for other plants, like [[Sphagnum|peat moss]] when conditions are right, and animals, many of which are very rare. Gradually the lake closes, and young [[peat]] may form, forming a [[fen]]. In lowland river valleys, where a river can [[meander]], the presence of peat is explained by the infilling of historical [[oxbow lake]]s. In the very last stages of [[succession]], [[tree]]s can grow in, eventually turning the wetland into a [[forest]].

Some lakes can disappear seasonally. These are called [[intermittent lake]]s and are typically found in [[Karst|karstic terrain]]. A prime example of an intermittent lake is [[Lake Cerknica]] in [[Slovenia]].

Sometimes a lake will disappear quickly. On [[3 June]], [[2005]], in [[Nizhny Novgorod Oblast]], [[රුසියාව]], a lake called [[Lake Beloye (Nizhny Novgorod Oblast)|Lake Beloye]] vanished in a matter of minutes. News sources reported that government officials theorized that this strange phenomenon may have been caused by a shift in the soil underneath the lake that allowed its water to drain through channels leading to the [[Oka River]].<ref>[http://www.mtstandard.com/articles/2005/06/04/newsnationworld/hjjejdjghhjejd.txt :: The Montana Standard ::<!-- Bot generated title -->]</ref>

The presence of ground permafrost is important to the persistence of some lakes. According to research published in the journal ''Science'' ("Disappearing Arctic Lakes," June 2005), thawing permafrost may explain the shrinking or disappearance of hundreds of large Arctic lakes across western Siberia. The idea here is that rising air and soil temperatures thaw permafrost, allowing the lakes to drain away into the ground.

[[Neusiedler See]], located in [[Austria]] and [[Hungary]], has dried up many times over the millennia. As of 2005, it is again rapidly losing water, giving rise to the fear that it will be completely dry by 2010.

Some lakes disappear because of human development factors. The shrinking [[Aral Sea]] is described as being "murdered" by the diversion for irrigation of the rivers feeding it.

{{see also|Prairie Lake}}

== Extraterrestrial lakes ==
[[ගොනුව:Iosurface gal.jpg|thumb|220px|Io exhibits extraordinary variations in color and brightness as shown in this color-enhanced image.]]
At present the surface of the planet [[Mars (planet)|Mars]] is too cold and has too little [[atmospheric pressure]] to permit the pooling of liquid water on the surface. Geologic evidence appears to confirm, however, that ancient lakes once formed on the surface. It is also possible that volcanic activity on Mars will occasionally melt subsurface ice creating large lakes. Under current conditions this water would quickly freeze and evaporate unless insulated in some manner, such as by a coating of volcanic ash.

<!-- source: http://saturn.jpl.nasa.gov/multimedia/images/image-details.cfm?imageID=2214 -->
Only one world other than Earth is known to harbor lakes, Saturn's largest moon, [[Titan (moon)|Titan]]. Photographs and spectroscopic analysis by the [[Cassini-Huygens]] [[spacecraft]] show liquid [[ethane]] on the surface, which is thought to be mixed with liquid [[methane]].

[[Jupiter (planet)|Jupiter]]'s small moon [[Io (moon)|Io]] is volcanically active due to tidal stresses, and as a result [[sulfur]] deposits have accumulated on the surface. Some photographs taken during the [[Galileo spacecraft|Galileo mission]] appear to show lakes of liquid sulfur on the surface.<ref>
{{
cite web
|url = http://www.nineplanets.org/io.html
|author=The Nine Planets Solar System Tour
|accessdate=2008-08-07
|title=Io
}}
</ref>

There are dark basaltic plains on the [[Moon]], similar to [[lunar mare|lunar maria]] but smaller, that are called ''lacus'' (singular ''lacus'', [[Latin]] for "lake") because they were thought by early astronomers to be lakes of water.

== Notable lakes ==
<!--[[Image:Titan North Pole Lakes PIA08630.jpg|thumb|Lakes on [[Titan (moon)|Titan]]]]-->
* [[Lake Michigan-Huron]] is the '''largest lake by surface area''': 117,350&nbsp;km². It also has the longest lake coastline in the world: 8,790 km. If Huron and Michigan are considered two lakes, [[Lake Superior]] is the largest lake, with 82,414&nbsp;km². However, Huron is still has the longest coastline at 6,157 km (2980 km excluding the coastlines of its many inner islands). The world's smallest geological ocean, the [[Caspian Sea]], at 394,299&nbsp;km² has a surface area greater than the six largest freshwater lakes combined, and it frequently cited as the world's largest lake.
* The '''deepest''' lake is [[Lake Baikal]] in [[Siberia]], with a bottom at 1,637&nbsp;m. Its '''mean depth''' is also the greatest in the world (749 m) <br /> It is also the world's '''largest lake by volume''' (23,600&nbsp;km³, though smaller than the Caspian Sea at 78,200&nbsp;km³), and the second longest (about 630 km from tip to tip).
* The '''longest''' freshwater lake is [[Lake Tanganyika]], with a length of about 660 km (measured along the lake's center line).<br /> It is also the second deepest in the world (1,470 m) after lake Baikal.
* The world's '''oldest''' lake is [[Lake Baikal]], followed by [[Lake Tanganyika]] ([[Tanzania]]).
* The world's '''highest''' lake is the crater lake of [[Ojos del Salado]], at {{Convert|6390|m|ft|0}}.<ref>[http://www.andes.org.uk/peak-info-6000/ojos-del-salado-info.asp Andes Website - Information about Ojos del Salado volcano, a high mountain in South America and the World's highest volcano<!-- Bot generated title -->]</ref> The [[Lhagba Pool]] in [[Tibet]] at {{Convert|6368|m|ft|0|abbr=on|abbr=on}} comes second.<ref>[http://www.highestlake.com/ Highest Lake<!-- Bot generated title -->]</ref>
* The world's '''highest''' commercially navigable lake is [[Lake Titicaca]] in [[Peru]] and [[බොලිවියාව]] at {{Convert|3812|m|ft|0|abbr=on}}. It is also the largest freshwater (and second largest overall) lake in [[South America]].
* The world's '''lowest''' lake is the [[Dead Sea]], bordering [[Israel]], [[Jordan]] at 418&nbsp;m (1,371&nbsp;ft) below sea level. It is also one of the lakes with highest [[salt]] concentration.
* [[Lake Huron]] has the '''longest lake coastline''' in the world: about 2980 km, excluding the coastline of its many inner islands.
* The largest [[island]] in a freshwater lake is [[Manitoulin Island]] in [[Lake Huron]], with a surface area of 2,766&nbsp;km². [[Lake Manitou]], located on Manitoulin Island, is the largest lake on an island in a freshwater lake.
* The largest lake located on an island is [[Nettilling Lake]] on [[Baffin Island]].
* The largest lake in the world that drains naturally in two directions is [[Wollaston Lake]].
* [[Lake Toba]] on the island of [[Sumatra]] is located in what is probably the largest resurgent [[caldera]] on [[Earth]].
* The largest lake located completely within the boundaries of a single city is [[Lake Wanapitei]] in the city of [[Greater Sudbury|Sudbury]], [[Ontario]], [[Canada]].<br /> Before the current city boundaries came into effect in 2001, this status was held by [[Lake Ramsey]], also in Sudbury.
* [[Lake Enriquillo]] in [[Dominican Republic]] is the only saltwater lake in the world inhabited by [[crocodile]]s.
* [[Lake of the Ozarks]] is one of the United States largest man made lakes, created by the [[Bagnell Dam]] <ref>[http://www.lakeozark.com Lake of the Ozarks, Missouri, the premier vacation spot in the Midwest<!-- Bot generated title -->]</ref>

=== Largest by continent ===
The largest lakes (surface area) by [[continent]] are:
* '''Africa''' - [[Lake Victoria]], also the second largest freshwater lake on [[Earth]]. It is one of the [[Great Lakes of Africa]].
* '''Antarctica''' - [[Lake Vostok]] (subglacial)
* '''Asia''' - [[Caspian Sea]], also the largest on Earth. However, Europe-Asia border is conventionally drawn through it - the largest entirely in Asia is [[Lake Baikal]].
* '''ඕස්ට්‍රේලියාව''' - [[Lake Eyre]]
* '''Europe''' - [[Lake Ladoga]], followed by [[Lake Onega]], both located in northwestern [[රුසියාව]].
* '''North America''' - [[Lake Michigan-Huron]]
* '''South America''' - [[Lake Titicaca]], which is also the highest navigable body of water on Earth at 3,821&nbsp;m above sea level.

'''Note''': [[Lake Maracaibo]] is considered by far the largest lake in South America. Because it lies at sea level, however, and has a relatively wide opening to sea, it is better described as a bay.

== See also ==
{|
|-valign=top
|
* [[List of lakes]]
* [[වැව]]
* [[පොකුණ]]
* [[සාගරය]]
* [[List of lakes in Austria]]
* [[Loch]]
* [[Lough]]
* [[Pond]]
* [[Lagoon]]
* [[Liman (landform)|Liman]]
|
* [[Slough (wetland)]]
* [[Mere (lake)]]
* [[Geography]]
* [[Tarn (lake)|Tarn]]
* [[Deep lake water cooling]]
* [[Angling]]
* [[Lake monster]]
* [[Limnology]]
* [[Lentic ecosystems]]
|}

== References ==
{{reflist}}
{{Refimprove|date=February 2008}}

== External links ==
{{linkfarm}}
{{commonscat|Lakes}}
{{wiktionary}}
* [http://www.ilec.or.jp/database/index/idx-lakes.html Lakes Database]
* [http://www.mlswa.org/lkclassif1.htm Lake Classification Systems]
* [http://www.midwestlakes.org Midwest Lakes Policy Center]

[[ප්‍රවර්ගය:විල්| ]]
[[ප්‍රවර්ගය:ජලය]]
[[ප්‍රවර්ගය:ස්වභාධර්මය]]

13:28, 21 මාර්තු 2014 තෙක් සංශෝධනය

ගොඩබිමින් වටවූ ස්වභාවිකව විශාල මිරිදිය ජලස්කන්ධයක් රැස්වන භූ අවපාතයන් විල් නම් වේ.

"https://si.wikipedia.org/w/index.php?title=විල්&oldid=291150" වෙතින් සම්ප්‍රවේශනය කෙරිණි