What occurs when high tides are at their highest and low tides are at their lowest?

Answer 1

I.INTRODUCTION

Tide, periodic rise and fall of all ocean waters, including those of open sea, gulfs, and bays, resulting from the gravitational attraction of the moon and the sun upon the water and upon the earth itself. See Gravitation.

II.LUNAR TIDES

The moon, being much nearer to the earth than the sun, is the principal cause of tides. Because the force of gravity decreases with distance, the moon exerts a stronger gravitational pull on the side of the earth that is closer to it and a weaker pull on the side farther from it. The earth does not respond to this variation in strength because the planet is rigid instead, it moves in response to the average of the moon's gravitational attraction. The world's oceans, however, are liquid and can flow in response to the variation in the moon's pull. On the side of the earth facing the moon, the moon's stronger pull makes water flow toward it, causing a dome of water to rise on the earth's surface directly below the moon. On the side of the earth facing away from the moon, the moon's pull on the oceans is weakest. The water's inertia, or its tendency to keep traveling in the same direction, makes it want to fly off the earth instead of rotate with the planet. The moon's weaker pull does not compensate as much for the water's inertia on the far side, so another dome of water rises on this side of the earth. The dome of water directly beneath the moon is called direct tide, and the dome of water on the opposite side of the earth is called opposite tide.

As the earth rotates throughout the day, the domes of water remain aligned with the moon and travel around the globe. When a dome of water passes a place on the earth, that place experiences a rise in the level of the ocean water, known as high tide or high water. Between successive high tides the water level drops. The lowest water level reached between successive high tides is known as low tide or low water. Low and high tides alternate in a continuous cycle. The variations that naturally occur in the level between successive high tide and low tide are referred to as the range of tide. At most shores throughout the world, two high tides and two low tides occur every lunar day, the average length of a lunar day being 24 hours, 50 minutes, and 28 seconds. One of these high tides is caused by the direct-tide dome and the other by the opposite-tide dome. Two successive high tides or low tides are generally of about the same height. At various places outside the Atlantic Ocean, however, these heights vary considerably; this phenomenon, which is known as diurnal inequality, is not completely understood at the present time.

III.SOLAR TIDES

Tides

The sun likewise gives rise to two oppositely situated domes, but because the sun is far from the earth, its tide-raising force is only about 46 percent that of the moon. The sum of the forces exerted by the moon and sun result in two sets of domes, the positions of which depend on the relative positions of the sun and moon at the time. During the periods of new and full moon, when the sun, moon, and earth are directly in line, the solar and lunar domes coincide. This results in the condition known as spring tides, in which the high tide is higher and the low tide is lower than usual. When the moon is in first or in third quarter, however, it is at right angles to the sun relative to the earth, and the height of the tides is subject to the opposing forces of the sun and moon. This condition produces neap tides, in which the high tide is lower, and the low tide is higher, than normal. Spring and neap tides occur about 60 hours after the corresponding phases of the moon, the intervening period of time being known as the age of the tide or age of the phase inequality. The interval of time between the crossing of a meridian by the moon at one point and the next high tide at that point is called the lunitidal interval, or the high-water interval for that point. The low-water interval is the period between the time the moon crosses the meridian and the next low tide. Average values for the high-water lunitidal intervals during periods of new and full moon are known as the establishment of the port. Values for the intervals during other periods of the month are often referred to as the corrected establishment.

IV.TIDAL CURRENTS AND WAVES

Tidal Pool

Tidal PoolThe fluctuation of the tide allows for a unique environment along shorelines. The current continually circulates and replenishes a rich supply of nutrients along beaches, but organisms living there must be adapted to both buffeting waves and frequent shifts from open air to complete submersion. Marine organisms adapt to the constantly changing surroundings in a variety of ways. Starfish use suction-cup feet, barnacles fix permanently to large objects like rocks and boats, and seaweed anchors firmly to the ocean floor. When the tide goes out, pockets of water remain trapped in rocks, depressions in the sand, and natural basins called tidal pools, like the one shown here during low tide.Encarta EncyclopediaPat O'Hara Photography

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Accompanying the vertical rise and fall of water are various horizontal or lateral movements commonly known as tidal currents or tidal streams, which are very different from the common ocean currents (see Ocean and Oceanography). In confined areas, a tidal current flows for about 6 hours, 12 minutes in an upstream or shoreward direction, corresponding to high tide; it then reverses and flows for approximately the same time in the opposite direction, corresponding to low tide. During the period of reversal, the water is characterized by a state of rest, or calm, known as slack water or slack tide. A current flowing toward the shore or upstream is called flood current; that flowing in a direction away from land or downstream is known as ebb current.

At various times gigantic waves strike the surrounding shore with tremendous force and cause considerable damage to life and property. Although sometimes called tidal waves, these waves are not caused by tidal phenomena. Earthquakes, undersea volcanic eruptions, and underwater landslides can cause large waves to wash ashore that are known as tsunamis, while hurricanes can cause a dome of water to wash ashore that is known as a storm surge.

Another related phenomenon is the seiche, which usually occurs in landlocked seas, coves, bays, or lakes, such as San Francisco Bay in California and Lake Geneva in Switzerland. The water surface is observed to oscillate between a few centimeters and several meters mainly because of tidal forces or local variations in atmospheric pressure aided by high winds, but sometimes as a result of a distant seismic shock. The movement of water occurs in long waves and may last from a few minutes to several hours.

V.TIDAL ENERGY

The energy of tides has been harnessed to produce electricity. In the summer of 1966, a tidal power plant with a capacity of 240,000 kw went into operation on the Rance River, an estuary of the English Channel in northwestern France. The incoming tide of the river flows through a dam, driving turbines, and then is trapped behind the dam. When the tide ebbs, the trapped water is released and flows back through the dam, again driving the turbines. Such tidal power plants are most efficient if the difference between high and low tides is great, as in the Rance estuary, where the difference is 8.5 m (28 ft). The highest tides in the world occur in the Bay of Fundy in Canada, where the difference between high and low tide is about 18 m (about 60 ft). The erection of a tidal power plant across Passamaquoddy Bay, an arm of the Bay of Fundy, has long been contemplated; however, the project has not yet been begun.

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Answer 2

Spring tides are those that have the greatest difference between high and low tides. Neap tides have the lowest difference. Beavers can fly did you know that!!!!

Answer 3

The sea facing the moon is pulled by the gravity pull causing tides.

Answer 4

We have high and low tides because of the gravity and the moon.

Answer 5

High tides are when currents are moving at a fast speed and low tides are when currents are moving at normal speed

Answer 6

the moon has a different gravity effect causing low or high tides

Answer 7

Tidal maximums and Tidal minimums. These two Incidents are not co-incidental.

Answer 8

The tides are caused by the pull of the moon travelling around the planet (and also to some extent by the sun).

Answer 9

High and low tides