A rip current, often simply called a rip, or by the misnomer rip tide, is a specific kind of water current which can occur near beaches with breaking waves. A rip is a strong, localized, and narrow current of water which moves directly away from the shore, cutting through the lines of breaking waves like a river running out to sea, and is strongest near the surface of the water.
Rip currents can be hazardous to people in the water. Swimmers who are caught in a rip current and who do not understand what is going on, and who may not have the necessary water skills, may panic, or exhaust themselves by trying to swim directly against the flow of water. Because of these factors, rips are the leading cause of rescues by lifeguards at beaches, and rips are the cause of an average of 46 deaths by drowning per year in the United States.
A rip current is not the same thing as undertow, although some people use the term incorrectly when they often mean a rip current. Contrary to popular belief, neither rip nor undertow can pull a person down and hold them under the water. A rip simply carries floating objects, including people, out beyond the zone of the breaking waves.
Rip current velocities also typically increase as wave heights increase. An increase in the height of incoming waves can result in sudden increases in water depth and rip current velocities. These sudden changes or pulses in water depth and current speed can catch bathers off-guard. Rip current pulsations are extremely dangerous to all swimmers! .
While average rip current velocities of 1 to 2 feet per second do not pose serious hazards to strong swimmers, rip currents may rapidly reach or exceed velocities of 3 feet per second. Also, rapid fluctuations or pulses in wave groups can quickly generate rip currents with extreme velocities that have been measured up to 8 feet per second – this is faster than an Olympic swimmer can sprint! If a swimmer is caught in a rip current, attempting to swim directly back to shore against the seaward flowing current can result in exhaustion and possible drowning.
Rip currents can often occur on a gradually shelving shore where breaking waves approach the shore parallel to it, or where underwater topography encourages outflow at a specific area. Rip currents can form at the coasts of oceans, seas, and large lakes, whenever there are waves of sufficient energy. The location of rip currents can be difficult to predict; whereas some tend to recur always in the same places, others can appear and disappear suddenly at various locations along the beach. The appearance and disappearance of rip currents is dependent on the bottom topography and the exact direction that the surf and swells are coming in from.
Rip currents have a characteristic appearance, and, with some experience, they can be visually identified from the shore before entering the water. This is useful to lifeguards, swimmers, surfers, boaters, divers and other water users, who may need to avoid a rip, or in some cases make use of the current flow. Rip currents often look a bit like a road or a river running straight out to sea, and are easiest to notice and identify when the zone of breaking waves is viewed from a high vantage point. The following are some characteristics that can be used to visually identify a rip:
- A noticeable break in the pattern of the waves — the water often looks flat at the rip, in contrast to the lines of breaking waves on either side of the rip.
- A "river" of foam — the surface of the rip sometimes looks foamy, because the current is carrying foam from the surf out to open water.
- Different color — the rip may differ in color from the surrounding water; it is often more opaque, cloudier, or muddier, and so, depending on the angle of the sun, the rip may show as darker or lighter than the surrounding water.
- It is sometimes possible to see that foam or floating debris on the surface of the rip is moving out, away from the shore. In contrast, in the surrounding areas of breaking waves, floating objects are being pushed towards the shore.
To claim credit for this Earthcache you must do the following: .
1. Post a picture of yourself (face not required) or a personal item at the sign.
2. What is the average velocity needed to form a rip current?
3. Name 2 ways to identify Rip Currents.
4. Did you see any rip currents during your visit?
5. Look at the sign at the top of the beach entrance stairs near the pavilion about rip currents. What do the green arrows represent?
6. From the same sign finish this sentence: “Rip currents are powerful ____________”
Information from Wikipedia and National Ocean Service