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.
Last modified September 19, 2008 by Lisa Gardiner.
Shop Windows to the Universe Science Store!
The Spring 2010 issue of The Earth Scientist
, focuses on the ocean, including articles on polar research, coral reefs, ocean acidification, and climate. Includes a gorgeous full color poster!
You might also be interested in:
If you sneeze into a pile of dust the little particles fly everywhere, but if you sneeze into a pile of rocks, they will stay put. It takes more force than a sneeze to move those rocks. Winds and water...more
When water or wind slows down, sediment can no longer be carried in it. The particles of sediment fall through the water or air and form a blanket of sediment on the bottom of a river, a lake, ocean,...more
The water at the ocean surface is moved by powerful wind. The wind is able to move the top 400 meters of the ocean. This moving water is called surface ocean currents. Surface ocean currents form large...more
An aquifer is the name for a layer of rock which is capable of holding a large amount of water. Some layers are better at holding water than others, for example a layer of sandstone can hold a good deal...more
Limestone is an example of a carbonate. Other examples of carbonates include calcite, dolomite, and marble. Limestone dissolves easily in rainwater, especially rainwater which is loaded with carbonic acid....more
The deep ocean waters are under pressure and are much colder than layers of the ocean which are closer to the surface. Dissolved carbon dioxide seems to be absent from the deep ocean water and as a result...more
Have you ever left a glass of water out for a long time? Did you notice that the water disappears after a few days? That's because it evaporated! Evaporation is when water passes from a liquid to a gas....more