A rip current is a strong flow of water returning seaward from the shore. It is often mistakenly called a "rip tide," though the occurrence is not related to the tides. Colloquially a rip current is known simply as a rip, or the misnomer undertow. Although rip currents would exist even without the tides, tides can make an existing rip much more dangerous (especially low tide). Typical flow is at 0.5 metres per second and can be as fast as 2.5 metres per second. Rip currents can move to different locations on a beach break, up to a few hundred feet a day. They can occur at any beach with breaking waves, including the world's oceans, seas and large lakes such as the Great Lakes.
There are signs to look for in the water to see if a rip current is present. Rip currents can be recognized by unusually calm waters, caused by the channel of water flowing out. The color of the water may be different from the surrounding area. Also, the waterline is lower on the shore near a rip current. It is advisable to look for the existence of a rip current before heading into the water.
Rip currents can also be extremely useful for surfers as they save the effort of having to paddle out to catch a set. They can also be used by lifeguards, who can use them to get out from the shore to perform a rescue much quicker than they could by swimming/paddling through the waves.
While the precise conditions leading to a rip current are not known, the general picture is as follows. When wind and waves push water towards the shore, the previous backwash is often pushed sideways by the oncoming waves. This water streams along the shoreline until it finds an exit back to the sea. The resulting rip current is usually narrow and located in a trench between sandbars, under piers or along jetties. The current is strongest at the surface, and can dampen incoming waves, leading to the illusion of a particularly calm area, luring some swimmers in. Rip currents are stronger when the surf is rough (such as during high onshore winds, or when a strong hurricane is far offshore) or when the tide is low.
There are signs to look for in the water to see if a rip current is present. Rip currents can be recognized by unusually calm waters, caused by the channel of water flowing out. The color of the water may be different from the surrounding area. Also, the waterline is lower on the shore near a rip current. It is advisable to look for the existence of a rip current before heading into the water.
Rip currents can also be extremely useful for surfers as they save the effort of having to paddle out to catch a set. They can also be used by lifeguards, who can use them to get out from the shore to perform a rescue much quicker than they could by swimming/paddling through the waves.
While the precise conditions leading to a rip current are not known, the general picture is as follows. When wind and waves push water towards the shore, the previous backwash is often pushed sideways by the oncoming waves. This water streams along the shoreline until it finds an exit back to the sea. The resulting rip current is usually narrow and located in a trench between sandbars, under piers or along jetties. The current is strongest at the surface, and can dampen incoming waves, leading to the illusion of a particularly calm area, luring some swimmers in. Rip currents are stronger when the surf is rough (such as during high onshore winds, or when a strong hurricane is far offshore) or when the tide is low.
Diagram of a rip current
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