The Tidal Waves

First of all, tide is the rise and fall of water caused by gravitational forces of the moon and sun on the oceans of the earth. Generally speaking, tidal cycles contain two high tides and two low tides each day. During the time between high and low tides there will obviously be current flow. The time between high and low tides is a little over 6 hours and the entire tidal cycle repeats itself approximately fifty minutes later each day. So if you know that low tide is at 0800 today you can estimate that it will be at least 0850 tomorrow.

The tidal bulge that occurs during high tide in the world ocean follows the revolution of the moon and the earth rotates eastward through the bulge once every 24 hours and fifteen minutes. The moon appears to rotate around the earth every day. However, it is the earth's rotation that gives this appearance. The moon actually orbits the earth in an elliptical pattern, taking 27.3 days to complete one orbit.

Earth is also being pulled towards the Moon and away from the water. When the Moon is full, or new, the gravitational pull of the Moon and the Sun are combined. At these times the high tides are very high and the low tides are very low. This is known as Spring High Tide. Spring tides are especially strong tides (they have nothing to do with the season Spring). They occur when the Earth and the Sun and the Moon are in alignment. The gravitation forces of the Moon and the Sun both contribute to the tides. The Moon is responsible for 56% of the Earth's tidal energy. P.S. Ð'- The Moon is nearly 240,000 miles away from the Earth. The actual height of the tide is influenced by the shape of the coastline and depth of the water.

The knowledge of the height of tides, both low and high, is vital for many functions including navigation, fishing, and construction of coastal facilities. Due to the rotation of the Earths and the Moon, the tidal cycle is about 24 hours and fifty two minutes long. During this time, any point on the Earth's surface experiences two high tides and two low tides. Winds and currents also move the surface of the water causing waves.

The gravitational pull of the Moon tugs on the surface of the ocean until its surface mounds up and outward in the direction of the moon. When the mound of water has reached the highest point is called high tide. On the side of the earth opposite the moon, the centrifugal force caused by the earth's rotation produces another mound of water and high tide on the opposite side of the earth. Somewhere in between these two high tides are two flat areas on the surface of the ocean, these are called low tides.

The earth's nearby moon is about 2.17 tines as effective as the m ore massive sun in raising tides on the earth, even though the sun exerts a much greater total force on the earth than does