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
Ocean waves often approach a coastline at an angle. This moves water along the coast in a longshore current. Longshore currents grow stronger when the incoming waves are closer to perpendicular to the beach than parallel. The currents also are stronger if the waves are very large, and if the beach has a steep slope.
Longshore currents move sand along the beach, eroding it from some areas and depositing it in other areas. This process is called longshore drift and it is able to, over time, move entire islands in the direction of the current. In areas that have strong longshore drift maps need to be redrawn as the shape of the coastline - the location of channels and sand spits - changes over time.
Longshore currents can carry more than just sand. They can carry people away too. Thus, these currents can be very dangerous for people swimming in the ocean. The dangerous aspect of a longshore current is called a rip current. It forms as part of a longshore current is drawn away from the coast – away from the beach. This happens usually where there is a change in the shape of the seafloor like a break in a sandbar.
The water in a rip current moves at one to two feet per second and some are as fast as eight feet per second. If a person swimming is caught in a rip current, they will be swept far from shore. But because rip currents only happen in isolated areas, usually not more than 25 meters (80 feet) wide, swimming parallel to the shore should get the person out of the rip current zone. The most important thing is not to panic. Moving water is a powerful force and swimming against it when caught in a rip current would be exhausting.
Shop Windows to the Universe Science Store!
We have beautiful specimens of banded iron formation
in our online store
from Nature's Own, along with many other mineral
You might also be interested in:
Sneeze into a pile of dust and the particles fly everywhere. Sneeze into a pile of rocks and they stay put. That’s because they have more mass. You need more force than a sneeze to move those rocks. Wind...more
When water or wind loses energy and 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,...more
The water at the ocean surface is moved primarily by winds. Large scale winds move in specific directions because they are affected by Earth’s spin and the Coriolis Effect. Because Earth spins constantly,...more
The ocean and life in the ocean shape the features of the Earth. Fundamental Concept 2a. Many earth materials and geochemical cycles originate in the ocean. Many of the sedimentary rocks now exposed on...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
Carbonate is a name for rocks and minerals which contain a certain form of carbon/oxygen compound known as CO32-. (CO32- is also known as the molecule carbonate). Limestone is an example of a calcium carbonate,...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