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| [[File:lighterstill.jpg]][[File:Undertow-by-Steve-Ellis.jpg|right|frame]] | | [[File:lighterstill.jpg]][[File:Undertow-by-Steve-Ellis.jpg|right|frame]] |
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− | *[http://en.wikipedia.org/wiki/19th_century 1817] | + | *[https://en.wikipedia.org/wiki/19th_century 1817] |
| ==Definitions== | | ==Definitions== |
| *1: the current beneath the [[surface]] that sets seaward or along the beach when [[waves]] are breaking upon the shore | | *1: the current beneath the [[surface]] that sets seaward or along the beach when [[waves]] are breaking upon the shore |
| *2: an underlying current, [[force]], or tendency that is in [[opposition]] to what is apparent | | *2: an underlying current, [[force]], or tendency that is in [[opposition]] to what is apparent |
| ==Description== | | ==Description== |
− | '''Undertow''' is a subsurface [[flow]] of [[water]] returning seaward from shore as result of [[wave]] action. This type of shore current can play a role in material deposition such as creating [http://en.wikipedia.org/wiki/Sand_bar sand bars]. | + | '''Undertow''' is a subsurface [[flow]] of [[water]] returning seaward from shore as result of [[wave]] action. This type of shore current can play a role in material deposition such as creating [https://en.wikipedia.org/wiki/Sand_bar sand bars]. |
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− | Undertows are below-surface rushes of water returning to [[sea]] after the water comes ashore as breaking [[waves]]. If there is an area under the waves where water can [[flow]] back out to sea more easily (such as a break in a sand bar) then a narrow [http://en.wikipedia.org/wiki/Rip_current rip current] can form. (A rip current is much more [[powerful]] and thus more [[hazardous]] to inexperienced people than ordinary undertow.) If however there is no [[weak]] point in the surf line, then the water that has run up onto the beach simply [[flows]] back out to sea under the waves, forming a simple undertow. | + | Undertows are below-surface rushes of water returning to [[sea]] after the water comes ashore as breaking [[waves]]. If there is an area under the waves where water can [[flow]] back out to sea more easily (such as a break in a sand bar) then a narrow [https://en.wikipedia.org/wiki/Rip_current rip current] can form. (A rip current is much more [[powerful]] and thus more [[hazardous]] to inexperienced people than ordinary undertow.) If however there is no [[weak]] point in the surf line, then the water that has run up onto the beach simply [[flows]] back out to sea under the waves, forming a simple undertow. |
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− | There is a popular misconception that the undertow is responsible for many [http://en.wikipedia.org/wiki/Drowning drownings] by somehow pulling people vertically down, so that they are then held under the water [[surface]]. While people can drown in any body of [[water]], even a puddle, undertow itself is relatively harmless; the great [[majority]] of drownings near the beach happen because people get caught in a [http://en.wikipedia.org/wiki/Rip_current rip current] which draws them out to [[sea]], and they are either poor swimmers or do not [[understand]] how to [http://en.wikipedia.org/wiki/Rip_current#Escaping_a_rip_current get free from a rip current]. | + | There is a popular misconception that the undertow is responsible for many [https://en.wikipedia.org/wiki/Drowning drownings] by somehow pulling people vertically down, so that they are then held under the water [[surface]]. While people can drown in any body of [[water]], even a puddle, undertow itself is relatively harmless; the great [[majority]] of drownings near the beach happen because people get caught in a [https://en.wikipedia.org/wiki/Rip_current rip current] which draws them out to [[sea]], and they are either poor swimmers or do not [[understand]] how to [https://en.wikipedia.org/wiki/Rip_current#Escaping_a_rip_current get free from a rip current]. |
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| [[Category: General Reference]] | | [[Category: General Reference]] |