Gourt > Kids and Teens > School Time > Science > The Earth > Oceanography > Tides (1)
The tide is the cyclic rising and falling of Earth's ocean surface caused by the tidal forces of the Moon and the Sun acting on the Earth. Tides cause changes in the depth of the sea, and also produce oscillating currents known as tidal streams, making prediction of tides important for coastal navigation (see Tides and navigation, below). The strip of seashore that is submerged at high tide and exposed at low tide, the intertidal zone, is an important ecological product of ocean tides.
The changing tide produced at a given location on the Earth is the result of the changing positions of the Moon and Sun relative to the Earth coupled with the effects of the rotation of the Earth and the local bathymetry (the underwater equivalent to topography). Though the gravitational force exerted by the Sun on the Earth is almost 200 times stronger than that exerted by the Moon, the tidal force produced by the Moon is about twice as strong as that produced by the Sun. The reason for this is that the tidal force is related not to the strength of a gravitational field, but to its gradient. The field gradient decreases with distance from the source more rapidly than does the field strength; as the Sun is about 400 times further from the Earth than is the Moon, the gradient of the Sun's field, and thus the tidal force produced by the Sun, is weaker.
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Oh how fast the tides change. After the most difficult 2yrs of my life, I now see that it was all part of God's plan 4 me.
Uhmanda_Brown (Amanda Brown) Sat, 12 Dec 2009 07:25:36 -0000
Oh how fast the tides change. After the most difficult 2yrs of my life, I now see that it was all part of God's plan 4 me.
For the rest of the tour, @SWStheband, JonnyCraig4L, and Tides Of Man will be doing something special on stage together. Come see the party!
SWStheband (SWS) Sat, 12 Dec 2009 07:11:39 -0000
For the rest of the tour, @SWStheband, JonnyCraig4L, and Tides Of Man will be doing something special on stage together. Come see the party!
Video: Tides of Time una significativa balada de la banda Holandesa Epica, de su último album⦠Simone Simons... http://tumblr.com/xtp4mosms
darkatreides (Isaac Robles) Sat, 12 Dec 2009 07:00:14 -0000
Video: Tides of Time una significativa balada de la banda Holandesa Epica, de su último album… Simone Simons... http://tumblr.com/xtp4mosms
Dangerous Tides http://kinomall.ru/movie/dangerous_tides.html?aid=2035
svetiksem (СвеÑлана) Sat, 12 Dec 2009 06:45:02 -0000
Dangerous Tides http://kinomall.ru/movie/dangerous_tides.html?aid=2035
In a couple years, tides have turned from boos to cheers. And in spite of the weather, we can learn to make it together.
_step_on_me_91 (Stephanie Hughes) Sat, 12 Dec 2009 06:32:23 -0000
In a couple years, tides have turned from boos to cheers. And in spite of the weather, we can learn to make it together.
It's noon and time to start reading Midnight Tides... #malazan
Jax (Xavier Roy) Sat, 12 Dec 2009 06:30:23 -0000
It's noon and time to start reading Midnight Tides... #malazan
Enchanted Learning: Tides - Brief description and illustrations about what causes the tide to rise and fall.
Meta Description: [ Tides are periodic rises and falls of large bodies of water. Tides are caused by the gravitational interaction between the Earth and the Moon. ]
How Does the Moon Affect Tides? - Boatsafe Kids answer concerns to water safety during low and high tides.
Moon Tides - Explains with graphs and pictures how the moon affects oceans. Includes the differences between lunar, spring, neap, high, and low tides.
NOVA: Sinking City of Venice - Program about the threat that Venice is under from rising tides.
Meta Description: [ This companion Web site to the NOVA program Sinking City of Venice shows the threat that Venice is under from rising tides, and describes one proposal to solve the problem - mobile gates placed at the entrances to Venice's lagoon. ]
Tide and Gravity Labs - Learn about basic concepts of gravitational force, and how it relates to tides on the Earth.
What are Tides? - Brief definition concerning the rise and fall of the tides.
Why Tides? - Animation showing the gravitational action of the sun and moon on the earth's oceans.
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