 | TIDES |
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http://itc.gsw.edu/faculty/bcarter/ocean/eqtide1.htm |
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Gravity and inertia act in opposition on the Earths oceans, creating tidal bulges on opposite sites of the planet. On the near side of the Earth (the side facing the moon), the gravitational force of the moon pulls the oceans waters toward it, creating one bulge. On the far side of the Earth, inertia dominates, creating a second bulge. |
http://home.hiwaay.net/~krcool/Astro/moon/moontides/ |
http://www.britannica.com/EBchecked/topic-art/101285/2300/Unequal-forces-on-two-tidal-bulges-leading-to-retardation-of |
How the tidal forces cause two tidal bulges. |
The M2 tidal constituent, the amplitude indicated by color. The white lines are cotidal lines spaced at phase intervals of 30 (a bit over 1 hr).[1] The amphidromic points are the dark blue areas where the lines come together. |
Diurnal and mixed tides |
tide classification |
Tidal datum |
tidal wave |
Frozen "Tidal Wave" The photographs were taken by scientist Tony Travouillon in Antarctica. Many of the images can be seen in a gallery on Travouillon''s website. The pictures do not show a giant wave somehow snap-frozen in the very act of breaking. The formation contains blue ice, and this is compelling evidence that it was not created instantly from a wave of water. Blue ice is created as the ice is compressed and trapped air bubbles are squeezed out. The ice looks blue because, when light passes through thick ice, blue light is transmitted back out but red light is absorbed |
Tidal Friction - Tides stretch the oceans, and to a small extent, the solid mass of a planet or satellite. In one complete rotation, the planet material keeps deforming and relaxing. This takes energy away from the rotation, transforming it into heat. |
The Equilibrium Theory of Tides This is sometimes called the theory of static tides, a theory that emerged for the first time in Isaac Newtons famed Principia. Having identified the tide-producing forces, Newton, and others who followed him, conceived of a hypothetical global ocean in static equilibrium with these forces an equilibrium calling for a prolate spheroid of water covering the earth. Prolate means that the sphere in question has been stretched along a line joining two poles; not the geographic poles in this case but the poles in line with the celestial body (moon or sun) causing the hypothetical ocean sphere to deform. Taking another look at the graphic illustrating the tractive forces in the previous module, one can easily imagine water converging on these poles to produce twin tidal bulges terms that are still very popular in modern day textbooks.
What are Lunar Tides
Tides are created because the Earth and the moon are attracted to each other, just like magnets are attracted to each other. The moon tries to pull at anything on the Earth to bring it closer. But, the Earth is able to hold onto everything except the water. Since the water is always moving, the Earth cannot hold onto it, and the moon is able to pull at it. Each day, there are two high tides and two low tides. The ocean is constantly moving from high tide to low tide, and then back to high tide. There is about 12 hours and 25 minutes between the two high tides
What are the different types of Tides
When the sun and moon are aligned, there are exceptionally strong gravitational forces, causing very high and very low tides which are called spring tides, though they have nothing to do with the season. When the sun and moon are not aligned, the gravitational forces cancel each other out, and the tides are not as dramatically high and low. These are called neap tides
Spring Tides
When the moon is full or new, the gravitational pull of the moon and sun are combined. At these times, the high tides are very high and the low tides are very low. This is known as a spring high tide. Spring tides are especially strong tides (they do not have anything to do with the season Spring). They occur when the Earth, the Sun, and the Moon are in a line. The gravitational forces of the Moon and the Sun both contribute to the tides. Spring tides occur during the full moon and the new moon.
Neap Tides
During the moon''s quarter phases the sun and moon work at right angles, causing the bulges to cancel each other. The result is a smaller difference between high and low tides and is known as a neap tide. Neap tides are especially weak tides. They occur when the gravitational forces of the Moon and the Sun are perpendicular to one another (with respect to the Earth). Neap tides occur during quarter moons.
The Proxigean Spring Tide is a rare, unusually high tide. This very high tide occurs when the moon is both unusually close to the Earth (at its closest perigee, called the proxigee) and in the New Moon phase (when the Moon is between the Sun and the Earth). The proxigean spring tide occurs at most once every 1.5 years
In the same manner, the Sun causes a semidiurnal solar tide, with a 12-hour period, and a diurnal solar tide, with a 24-hour period. In a complete description of the local variations of the tidal forces, still other partial tides play a role because of further inequalities in the orbital motions of the Moon and the Earth.
Dynamic Tides In contrast to static theory, the dynamic theory of tides recognizes that water covers only three-quarters of our planet and is confined to seas and ocean basins that are fixed on a rotating earth. Since solar as well as lunar tractive force nets (red arrows on green sphere) remain aligned with their respective celestial parents, an ocean or sea on this rotating earth experiences forces of constantly changing magnitude and direction (the earths crust is also affected by these forces, creating small but detectable earth tides).
The Dynamis theory of tides first proposed in 1775 by Laplace.
Tidal Friction
Tides stretch the oceans, and to a small extent, the solid mass of a planet or satellite. In one complete rotation, the planet material keeps deforming and relaxing. This takes energy away from the rotation, transforming it into heat.
The Equilibrium Theory
Tides
elliptical orbit: Keplers laws of planetary motion
Dynamic Tides
Frozen Tides
