A rip current forms when part of a longshore current is drawn away from the coast – perpendicular to the beach.
Courtesy of NOAA
Currents at the Coast
When waves get to the beach at an angle, water moves along the coast in a longshore current. Longshore currents grow stronger when the waves come towards the beach at a large angle, if the waves are large, and if the beach has a steep slope.
Longshore currents move sand along the beach, taking it from some areas and then leaving it in other areas. This process of moving sand is called longshore drift. It is able to, over time, move entire islands in the direction of the current. Places with longshore drift need new maps made as the shape of the coastline changes over time.
Longshore currents can carry more than just sand. They can carry people too. If a person swimming is caught in a rip current, they will be swept far from shore. Thus, these currents can be very dangerous. Rip currents form when part of a longshore current moves away from the beach. This happens usually where there is a change in the shape of the seafloor.
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