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What are Tides?

What are Tides?. Tides are one of the most reliable phenomena in the world. As the sun rises in the east and the stars come out at night, we are confident that the ocean waters will regularly rise and fall along our shores. What causes tides?.

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What are Tides?

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  1. What are Tides? Tides are one of the most reliable phenomena in the world. As the sun rises in the east and the stars come out at night, we are confident that the ocean waters will regularly rise and fall along our shores.

  2. What causes tides? • The gravitational forces of the moon and sun on the water causes the tides. • The moon, being nearest, has the greatest effect even though the sun is the larger of the two. • High tides are generated on the sides of the Earth nearest to and farthest from the moon

  3. The rise and fall of the tides play an important role in the natural world and can have a marked effect on maritime-related activities. Here, a ship's crew inspects the hull of their vessel. It became stranded on a sandbar following a rapidly receding tide.

  4. During new and full moon phases the moon, sun, and Earth are aligned causing a greater gravitational pull on the Earth. This results in higher high tides and lower low tides.

  5. How are Tides Predicted?

  6. Basically, tides are very long-period waves that move through the oceans in response to the forces exerted by the moon and sun. They appear as the regular rise and fall of the sea surface

  7. Gravity is one major force that creates tides.

  8. Unlike a 24-hour solar day, a lunar day lasts 24 hours and 50 minutes. This occurs because the moon revolves around the Earth in the same direction that the Earth is rotating on its axis. Since the Earth rotates through two tidal “bulges” every lunar day, we experience two high and two low tides every 24 hours and 50 minutes. High tides occur 12 hours and 25 minutes apart, taking six hours and 12.5 minutes for the water at the shore to go from high to low, and then from low to high.

  9. Tides are the regular and predictable periodic variations in sea level on the Earth that correspond to changes in the relative positions of the Moon and the Sun.

  10. This road in Hawaii cannot be used during high tide because it is under water.

  11. In Lynmouth, England you can really see how high the tides are every 12.5 hours. At low tide the harbor is dry and the boats sit on the harbor bottom, at high tide they are about 30 feet higher.

  12. Lynmouth at high tide.

  13. Charts that help us predict tides.

  14. Tide Chart Date Day Time Height Time Height Time Height Time Height Time Height 09/01/2004 Wed 06:03AM LDT 2.0 H 11:23AM LDT 1.0 L 06:15PM LDT 2.1 H 11:47PM LDT 1.0 L 09/02/2004 Thu 06:15AM LDT 2.0 H 12:07PM LDT 0.7 L 07:37PM LDT 2.0 H 09/03/2004 Fri 12:25AM LDT 1.4 L 06:20AM LDT 1.9 H 12:53PM LDT 0.6 L 09:11PM LDT 2.0 H 09/04/2004 Sat 01:01AM LDT 1.9 L 06:04AM LDT 2.0 H 01:44PM LDT 0.4 L 11:17PM LDT 2.1 H 09/05/2004 Sun 01:21AM LDT 2.0 L 03:24AM LDT 2.1 H 02:43PM LDT 0.4 L 09/06/2004 Mon 02:56AM LDT 2.3 H 03:50PM LDT 0.4 L 09/07/2004 Tue 03:24AM LDT 2.4 H 05:01PM LDT 0.4 L 09/08/2004 Wed 03:50AM LDT 2.4 H 06:04PM LDT 0.3 L 09/09/2004 Thu 04:05AM LDT 2.4 H 06:54PM LDT 0.3 L 09/10/2004 Fri 04:11AM LDT 2.4 H 07:35PM LDT 0.3 L 09/11/2004 Sat 04:16AM LDT 2.4 H 09:19AM LDT 2.0 L 12:37PM LDT 2.1 H 08:10PM LDT 0.3 L 09/12/2004 Sun 04:25AM LDT 2.3 H 09:02AM LDT 2.0 L 01:44PM LDT 2.1 H 08:42PM LDT 0.4 L 09/13/2004 Mon 04:37AM LDT 2.3 H 09:13AM LDT 1.9 L 02:44PM LDT 2.3 H 09:14PM LDT 0.6 L 09/14/2004 Tue 04:49AM LDT 2.3 H 09:37AM LDT 1.6 L 03:45PM LDT 2.3 H 09:47PM LDT 0.9 L 09/15/2004 Wed 05:00AM LDT 2.3 H 10:07AM LDT 1.3 L 04:49PM LDT 2.3 H 10:23PM LDT 1.1 L 09/16/2004 Thu 05:09AM LDT 2.1 H 10:42AM LDT 1.0 L 05:58PM LDT 2.3 H 11:00PM LDT 1.4 L 09/17/2004 Fri 05:11AM LDT 2.1 H 11:21AM LDT 0.7 L 07:18PM LDT 2.3 H 11:39PM LDT 1.9 L 09/18/2004 Sat 05:03AM LDT 2.1 H 12:07PM LDT 0.4 L 08:51PM LDT 2.4 H 09/19/2004 Sun 12:20AM LDT 2.1 L 04:38AM LDT 2.3 H 01:01PM LDT 0.1 L 10:48PM LDT 2.6 H 09/20/2004 Mon 01:01AM LDT 2.4 L 03:56AM LDT 2.6 H 02:05PM LDT 0.0 L 09/21/2004 Tue 01:35AM LDT 2.7 H 03:19PM LDT 0.0 L 09/22/2004 Wed 02:29AM LDT 2.9 H 04:37PM LDT 0.0 L 09/23/2004 Thu 02:57AM LDT 2.9 H 05:51PM LDT 0.0 L 09/24/2004 Fri 03:18AM LDT 2.7 H 06:56PM LDT 0.0 L 09/25/2004 Sat 03:35AM LDT 2.6 H 08:35AM LDT 2.1 L 12:30PM LDT 2.3 H 07:52PM LDT 0.1 L 09/26/2004 Sun 03:49AM LDT 2.4 H 08:41AM LDT 1.9 L 01:58PM LDT 2.4 H 08:42PM LDT 0.4 L 09/27/2004 Mon 04:02AM LDT 2.3 H 09:04AM LDT 1.6 L 03:13PM LDT 2.4 H 09:27PM LDT 0.9 L 09/28/2004 Tue 04:14AM LDT 2.3 H 09:35AM LDT 1.1 L 04:22PM LDT 2.4 H 10:09PM LDT 1.1 L 09/29/2004 Wed 04:25AM LDT 2.1 H 10:08AM LDT 0.9 L 05:29PM LDT 2.4 H 10:50PM LDT 1.6 L 09/30/2004 Thu 04:33AM LDT 2.1 H 10:44AM LDT 0.6 L 06:38PM LDT 2.4 H 11:29PM LDT 1.9 L 

  15. Tidal Predictions, including along the Gulf Coast • This website http://www.tides.com/tcpred.htm has about 20 locations along the Texas coast where tides are predicted for either today or tomorrow. You will have to select the Gulf Coast as your region and then get a list of the Gulf locations that are available. Once you submit your request, a chart and a table are prepared for screen viewing. You must have graphics capabilities to use this site. • Site will allow you to set areas, time length, manner of display http://tbone.biol.sc.edu/tide/sitesel.html • Using this difference table, you can manually compute good estimates of tidal levels using Galveston bay as a starting point. • Extensive list of links having to do with tidal predictions, etc. http://scilib.ucsd.edu/sio/tide • If you are interested in understanding tides better or having a more mathematical look at tidal action, this website http://math.math.sunysb.edu/~tony/t ides/index.html is for you

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