What causes a Oceans undertow?

Answer 1

Currents. The are acutally called Rip currents.

Here is an excerpt from wikipedia explainign the cause:

While the precise conditions leading to a rip current are not known, the general picture is as follows. When wind and waves push water towards the shore, the previous backwash is often pushed sideways by the oncoming waves. This water streams along the shoreline until it finds an exit back to the sea. The resulting rip current is usually narrow and located in a trench between sandbars, under piers or along jetties. The current is strongest at the surface, and can dampen incoming waves, leading to the illusion of a particularly calm area, luring some swimmers in.

Rip currents are stronger when the surf is rough (such as during high onshore winds, or when a strong hurricane is far offshore) or when the tide is low.

Answer 2

While the precise conditions leading to a rip current are not known, the general picture is as follows. When wind and waves push water towards the shore, the previous backwash is often pushed sideways by the oncoming waves. This water streams along the shoreline until it finds an exit back to the sea. The resulting undertow is usually narrow and located in a trench between sandbars, under piers or along jetties. The current is strongest at the surface, and can dampen incoming waves, leading to the illusion of a particularly calm area, luring some swimmers in.

Answer 3

This Site Might Help You.

RE:
What causes a Oceans undertow?

Answer 4

Riptides and undertows are related. Breaking waves approaching the beach carry water toward the beach. The water can't just pile up there: it has to escape back out to sea somehow. If there's a place along the beach where the waves aren't as strong, the piled-up water near the shore escapes through that weak spot, flowing back out to sea. This is a rip tide. If there is no spot with weaker surf, the piled-up water flows down and under the waves and back out to sea, forming an undertow.

Answer 5

The flow of water back out to sea from waves that have crashed ashore and are now receeding is a cause of undertow.

Another cause are the underwater current just offshore. They suck in additional water near the beach, which is drawn along the shore but also OUT to sea and DOWN to the depth of the current -- and these are the really dangerous undertows. These are strongest when the tide is going out. Sometimes you can see ripples ("tide rips") along the surface of the water indicating the edge of this current.

Answer 6

A common perception is that rip currents pull you underwater, but in reality they're roughly horizontal currents that gradually suck you further and further from the beach.

Here's how they originate: Waves break differently at different parts of a shore -- in some places the waves are strong and in others they are weak. These differing conditions carve out channels in sand bars that lie just off the beach. When water returns to the ocean, it follows the path of least resistance, which is typically through these channels.

This creates a strong and often very localized current capable of sweeping unsuspecting swimmers out to sea. The currents usually move at one to two feet per second but stronger ones can pull at up to eight feet per second. (On a track, Olympic sprinters cover about 34 feet per second.)

Heavy breaking waves can trigger a sudden rip current, but rip currents are most hazardous around low tide, when water is already pulling away from the beach.

Hurricanes, widely spaced swells, and long periods of onshore wind flow can also drum up stronger than normal currents. These conditions also create larger waves, which sometimes draw more people into the water.

is easy to be caught in a rip current. Most often it happens in waist deep water, experts say. A person will dive under a wave, but when they resurface they find they are much further from the beach and still being pulled away.

What they do next can decide their fate.

Those who understand the dynamics of rip currents advise remaning calm. Conserve energy. A rip current is like a giant water treadmill that you can't turn off, so it does no good to try and swim against it.

The United States Lifesaving Association (USLA) suggests trying to swim parallel to the shore and out of the current. Once you've gotten out of the current, you can begin swimming back to shore.

However, if it is too difficult to swim sideways out of the current, try floating or treading water and let nature do its thing. You'll wash out of the current at some point and can then make your way back to shore.

If neither of these options seems to be working for you, continue treading water and try to get the attention of someone on shore, hopefully a lifeguard.

Answer 7

The moon causes everything in the ocean tides,undertows you name it, anything

Answer 8

receding tides. the water that lapped on the shore returns to the sea and carries with it momentum and inertia. not visible on the surface, but take a trip to Spencer's or a science store and find one of those teeter totter sand/liquid things. Same principle. You can cause currents and watch the liquid.

Answer 9

Adhesion

Answer 10

http://en.wikipedia.org/wiki/Rip_current#Causes_and_occurrence