News to Me
News to Me
Getting Ripped |
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| Okay, let me apologize in advance since you may learn something this time,
I know I did. And no, I'm not talking emptying that sixer in your cooler or working on
those abs, we're talking rip tides.
It's a pretty serious subject since they claim a few folks every year. As a matter
of fact, rip tides are the primary cause of over 80 percent of ocean rescues. That's a
lot. |
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| Rip tides are formed
when waves break in shallow water in rapid succession. When the water that waves hurl on
shore cannot easily return, it becomes trapped and piles up inside the break near shore.
When this collection of water becomes sufficient, a current develops and begins seaward
looking for the path of least resistance. Where a underwater hole or canyon isn't
naturally occurring, the water erodes a channel as it moves; "this channelization
allows for a continuous flow of water, creating the rip current." Rips grow seasonally. The relatively calm surf of summer will fill many holes while harsh winter surf will create new ones which turn into rip tide locations. Therefore, in spring directly following winter storm activity, or following any rough sea activity for that matter, is when rip problems are at their worst. |
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| Some places seem to always have rips, this is primarily due to the underwater land topography and the shape of the shoreline. Where there are holes, or the topography makes it likely a channel will form following rough surf, a rip will occur and re-occur. Once a rip is formed they are supplied by water from feeder currents "...which collect from incoming waves and flow laterally along the beach into the main rip current." Steve mentioned that rips are also generated from adding sand to a beach, dredging the marina, or adding rocks to a jetty (re-fortifying), things that affects water flow. But Steve did want to make the point that during prolonged periods when surf is lacking rips may not appear in likely areas, but will certainly re-occur or resurface when the surf regains its strength. I've observed rips moving or shifting throughout the day, I asked Steve if this was my imagination and maybe just my paddling skills were lacking. Steve explained that Zuma for example, is known for its strong southerly current and rips seem to drift for a tower or so. The process of channelization is still at work here, water looking for the easiest path back. Strong currents are just constantly displacing water flows and shifting the channelization process. The South Bay has a powerful west swell in winter with a southerly current which is similar. Okay, how can someone identify a rip? "Although they can vary in appearance, they are usually recognized by appearing different from the surrounding surf. |
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| The rip may appear
as a brown, choppy river heading out to sea. Or, the rip may appear as a darker area of
water where waves are not breaking. Because the characteristics and locations of rip
currents may be constantly changing, the best way to locate a rip current is to ask a
professional Lifeguard."¹ |
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| everyone which is
far easier to do if folks aren't scattered all over the 31 miles of L. A. County Beaches.
We big strong swimmers thrashing around wherever we want is certainly at the very least
distracting. Shooting for the bright side again, think of all the half naked folks
you'll meet swimming within the flags. Moreover, the more we respect those red flags,
probably the less we have to put up with those dang black ball ones. There were other things I learned. Orange County lifeguards use a colored flag system to indicate danger conditions. A green flag indicates a generally safe condition, while yellow denotes caution and red indicates a hazardous condition. These flags are used for rip tides, as well as for other hazardous conditions including of all things, oil spills, ...yuck. Some other good trivia courtesy of Orange Coast College Professor Tom Garrison's book "OCEANOGRAPHY: An Invitation to Marine Science" is that tidal friction in general and on a global scale is gradually slowing the earth's rotation. The length of a day has grown longer and conversely the number of days in a year has decreased. Evidence suggests that 350 million years ago, a year contained between 400 and 410 days with each day some 22 hours long. Of course that works out to only a few hundredths of a second per century, but it's still cool, huh?! EP. ¹ http://www.LACountyLifeguards.org.
Rip Currents |
