Biodiversity and Evolution
What are the different types of surface currents?
Answered by Planet Green
Surface currents are created by the force of nearby winds and are found at or above depths of 328 feet (100 meters). The types of surface currents include surface ocean currents and coastal currents. As the name suggests, coastal currents occur at coastlines. These are the currents you experience in the water at a beach. The motion of surface currents influences the formation of land and waves. The weather pattern known as El Nino is created by an equatorial current carrying warm waters. Surface ocean currents are currents formed by global wind patterns out in the deep ocean.
Among the other kinds of surface current is one called a longshore current. They're caused by waves breaking at the shoreline. When a wave hits the shore from an angle, energy moves both parallel and perpendicular to the shore. The longshore current is a consequence of the parallel energy. This is the current that moves the water -- and people and objects in it -- down along the length of the beach. Longshore currents are responsible for longshore drift, the movement of sediment down along the coastline. While it sounds inconsequential enough, over time the drift actually causes spits and barrier islands to form.
Meanwhile, yet another current type, rip currents, aren't in a rush to hang around near the shoreline. Unlike longshore currents that move along the shore, rip currents rush out into the ocean, pulling with it foam, debris and possibly even people! They are created when water from crashed waves rushes through a narrow opening, such as through a break in a sandbar. These currents move with lots of force and can be dangerous to swimmers, so it's helpful to learn what visible hints can suggest a rip current. A visible difference in water color, a channel of rough water, an interruption in the shore-bound wave system or a line of foam headed out to sea are all clues the water might contain a rip current [source: NOAA].
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