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| http://www.ripcurrents.noaa.gov/ |
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| https://en.wikipedia.org/wiki/Rip_current |
A rip current, commonly referred to simply as a rip, or by the misnomer "rip tide", is one specific kind of water current that can be found near beaches. It is a strong, localized, and rather narrow current of water. It is strongest near the surface of the water, and it moves directly away from the shore, cutting through the lines of breaking waves.[1]
Rip currents can occur at any beach where there are breaking waves: on oceans, seas, and large lakes. The location of rip currents can be unpredictable: while some tend to recur always in the same place, others can appear and disappear suddenly at various locations near the beach.[2]
A rip current forms because breaking waves push water towards the land. Water that has been pushed up near the beach flows together (as feeder currents), and this water finds a place where it can flow back out to sea. The water then flows out at a right angle to the beach in a tight current called the "neck" of the rip, where the flow is most rapid. When the water in the rip current reaches outside of the lines of breaking waves, the flow loses power, and dissipates in what is known as the "head" of the rip. Sometimes tendrils of left-over current then actually curve back towards the shore.
Rip currents can be hazardous to people who are in the water. Swimmers or floaters who are caught in a rip and who do not understand what is going on, may not have the necessary water skills, may panic, or may exhaust themselves by trying to swim directly against the flow of water. Because of these factors, rips are the leading cause of rescues by lifeguards at beaches, and in the US rips are responsible for an average of 46 deaths from drowning each year.
A rip current is not the same thing as undertow, although some people use the latter term when they mean a rip current. Contrary to popular belief, neither rip nor undertow can pull a person vertically down and hold them under the water surface; A rip simply carries floating objects, including people, to an area outside the zone of the breaking waves.
Recognizing and identifying rips
There is a noticeable break in the pattern of the waves:
- the water often looks flat where the rip is, in contrast to the lines of breaking waves on either side of the rip.
- A "river" of foam: the surface of the rip sometimes looks foamy, because the water is churned up.
- Different color: the rip usually differs in color from the surrounding water; it is often more opaque, cloudier, or muddier, and so, depending on the angle of the sun, the rip may show as darker or lighter than the surrounding water.
- It is sometimes possible to see that foam or floating debris on the surface of the rip is moving out, away from the shore. In contrast, in the areas of breaking waves, floating objects are being pushed towards the shore.
https://en.wikipedia.org/wiki/Rip_current
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