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Tidal Clock
And How Tide Clocks Work
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Whatever your relationship with the sea, it is always important and useful to know the current position of the tide. Buy one of these tidal clocks for yourself or as a gift to someone who enjoys sailing, fishing or simply being near the sea, and you'll be getting something that will be useful for many years to come.
How does a tide clock work?
Due to the fact that the gravitational pull of the moon on the oceans is the major influence on the tides, tidal clocks work by timing the aparent motion of the moon around the earth. The actual true orbit of the moon takes 29 days, 12 hours, 44 minutes and 2.8 seconds, (ie 29.53 days) but as the earth is spinning on its own axis too, the moon appears to rise and set every day as the earth turns, in a similar way to how the sun appears to rise and set every day. The direction of the moon's actual 29.53 day cycle around the earth is the same direction as the turn of the earth''s axis. Therefore by the time the earth has turned once on its axis (which takes 24 hours), the moon has advanced around the earth a little. The advance of the moon in one day is 1/ 29.53 of its full cycle. The planet earth must therefore rotate for another 1/29.53 of a day (48.76 minutes) to arrive at where the moon was after the earth's initial 24 hour turn. You can take this further by realising that after these extra 48.76 minutes of the earth's travel, the moon has again moved forward a little more, but we're now getting into such exact figures that become slightly inappropriate when talking about the tide, as, although it the sun's influence is much less than that of the moon when it comes to tidal flow, the position of the sun does also have a small influence on the tidal flows.The sun's effect on the timing of tides is greates at times of the last quarter and first quarter of the moon. At this point the moon and sun are at right angles to each other when viewed from earth. This causes the high tides to be lower than usual, and low tides to be higher than usual, and can cause differences of up to half an hour in expected high and low tide times. Effectively then, we're talking about a period of around 24 hours 48.7 minutes between the moon appearing in the same part of our sky when viewed from earth. At first thought it would appear that this would give only one high tide per day, but in most areas there are actually two high tides and two low tides each day. This is due to the effects of gravitation on the solid body of the planet earth, and also the effect of centrifugal forces. The earth and moon actually have a combined centre of gravity around which both planetary objects circle. This center of gravity is not out there in space between the two bodies, but is actually inside the earth, as a result of the earth's much larger mass than the moon. This center of gravity, which is always in the direction of the moon, and the earth wobbles around this center, meaning that the side of the earth furthest away from the moon experiences a centrifugal force which pushes the liquid water of the seas outward. This effect is combined with the fact that the gravitational pull of the moon pulls the solid body of the earth, including the sea floor on the opposite side of the moon, toward the moon itself. The elipse of water, being liquid rather than a solid mass, is therefore higher on both the side closest and furthest to the moon. With two tides in one apparent orbit of the moon around the earth, and a period of 24 hours 48.7 minutes for each of these orbits, this gives a perion of around 12 hours 24 minutes between successive high tides. This is the time that it takes for tidal clocks to complete one rotation of their tide hand from one high tide to the next. On the opposite side of the high tide indicator, there is a low tide indicator, and most clocks also show a count-down style of "hours until high tide" and "hours until low tide". In many cases the tide clock will be combined with a normal 12 hour clock, either in an inner or outer ring of digits on the clockface. This can give you a total of up to 4 hands on the clock, which may look a little confusing at first. It's easy really though they're just the normal hour, minute and second hand which display the actual time of day, plus there's the extra hand for the tidal clock. |
 Oregon Scientif BAR386A Wireless Forecast With Temp DisplayOregon Scientific s Wireless Weather Forecaster displays 12. and 24hour weather forecasts monitors indoor and outdoor temperature and sets its integrated clock to the US Atomic Clock signal for precision time. Set up the main console indoors where it s convenient to read and set up the remote wireless sensor anywhere indoors or out to measure temperature and humidity from up to 100 feet away. Sunny rainy and cloudy weather conditions are depicted with simpletoread graphical icons. The wireless sensor features an LCD display that shows temperature and humidity levels wherever it s stationed. And since the clock automatically sets itself to the United States Atomic Clock it never needs adjusting for Daylight Saving Time. More great features: A moon phase indicator keeps you abreast of tidal conditions. The station s barometer indicates whether pressure is rising steady or falling. And a high/low temperature alarm sounds when preset levels have been breached. So if baby s room has gotten too cold the wine cellar has gotten too hot or if temperatures aren t right in the greenhouse you ll know it right away. For even more peace of mind an ice alert warns when temperatures have reached levels that might threaten pipes in the basement or elsewhere. The clock features a crescendo alarm with snooze function to ease you into the day. The weather station receives data from up to three remote sensors (two other extra sensors needed). The included sensor measures temperatures from twenty-two to 140 degrees F. Forecast icons display 1224 hour weather forecast. Displays the indoor and outdoor temperature. Automatically sets itself to the United States Atomic Clock never needs adjusting for Daylight Saving Time. Moon Phase indicator. three levels of pressure and temperature indicators: Rising Steady or Falling. High/low Temperature alarm. Ice Alert. Crescendo alarm with snooze function. Wireless sensor monitors inside/outside temperature. Threechannel temperature channel capabilities (extra sensors
Sale price $42.00
Save on normal price of $56.70
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 Tide Timer Clock Indoor/Outdoor Wall MountedTide Timer Clock Indoor/Outdoor Wall Mounted The Tide Time operates on lunar time so it consistently and accurately predicts the coming and going of the tides. The Tide Timer functions well on Atlantic tidal waters and on the Pacific Coast (with provided Pacific starting tables) ? will not predict Gulf of Mexico tides.
$45.99
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Cherry-finished Tide ClockChart the ebb and flow of the tides with this simple-to-read wall-mounted tide clock.
$99.00
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Personalized Nautical Tide ClockObserve your favorite United States coastal waterway whilst checking the tide with this Hand-crafted nautical clock.
$125.00
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Tide Mate III, Tide ClockTide Mate III, Tide Clock 645-527 Tide Mate IIIThis round table clock features a silvertoned case, polished silvertoned feet and circular spun silver finished outer ring with dark blue screening of "High Tide" and "Low Tide.".Dial is ocean blue with white graphics displaying hours remaining before the occurrence of the next low and high tide.Acrylic crystal with red arrow tide hand and silver second hand.Red tide arrow identifies the approximate position of the high and low tides for the Atlantic Ocean. Please note: this is not a precision instrument intended to accurately predict the tides.Includes a Velcro style hook and loop strip to hold the clock in place on your oceanbound vessel.Dimensions:H. 6-1/4" (16 centimeters)W. 6" (15 centimeters)D. 2" (5 centimeters)
$70.98
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Rip TideThe sequel to the acclaimed subsea adventure DARK LIFE. Ty has always known that the ocean is a dangerous place. Every time he swims beyond the borders of his family's subsea farm, he's prepared to face all manner of aquatic predators-sharks, squid, killer whales . . . What Ty isn't prepared to find in the deep is an entire township chained to a sunken submarine, its inhabitants condemned to an icy underwater grave. It's only the first clue to a mystery that has claimed hundreds of lives and stands to claim two more -- lives extremely precious to Ty and his Topsider ally, Gemma. Now in a desperate race against the clock, Ty and Gemma find themselves in conflict with outlaws, Seaguard officers, and the savage, trident-wielding surfs -- plus a menagerie of the most deadly creatures the ocean has to offer. Kat Falls brings to life the mysteries, marvels, and monsters of the deep in this fast-paced and inventive action-adventure.
$14.35
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