Moon’s pull

How moon pulls the water of sea

 Tides are caused by the gravitational pull of the moon on the earth. The sun, too, has its gravitational pull which is huge compared to the moon. But the moon is so much nearer the earth that its tide-rising force is more than twice as great as that of the sun. The ratio is about 9:4. Sometimes the moon and the sun pull together. The result is an unusually high tide. Sometimes they pull to different directions. 

Moon 's pull

The result is as unusually low tide. The sun can only help or hinder the tide raising effect of the moon’s pull. The moon’s pull affects the liquid-covering of the earth much more easily than the solid portions. The water on the side of the earth nearest to the moon gets heaped up into a great wave. This wall of water rushes onto the coast. 
Water level goes down in areas from where the water has been pulled up. Exactly opposite, on the other side of the earth, there rises another high tide. This is because the earth’s centre, being closer to the moon than the sea on the other side, gets pulled up towards the moon. This creates a vacuum, in the ocean, to fill which water comes rushing from right and left. 
Thus the moon’s pull produces two tides at one and the same time, at two opposite places of the earth. The two high tides naturally produce two low tides at two opposite places of the earth. As the moon races along its orbit, its pull keeps shifting from one part of the earth to another.
 Every six hours, the places of high tide have their low tide and those, of low tide get their high tide. Thus twice a day the water rises and twice a day it recedes on every sea coast. At new moon and full moon, the sun, the moon and the earth are practically in a straight line. The attractive force of the sun adds to the pull of the moon, five result is two flood tides much higher than the average. As a natural result, the low tides are lower.than the average.
 Such high tides are called spring tides.
 They occur twice in a lunar month. On the 7th and the 21 st days of the lunar month the pull of the moon exerts itself at right angles to the attracting force of the sun. In other words, the two bodies are opposed to each other. The tide-raising force of the moon is lessened. 
The result is a high tide much below the average height and a low tide that does not recede so far. There is less differences between high and low waters. Such lesser tides are called neap tides. There are many uses of the tidal waves. When high tide recedes, it leaves behind various kinds of sea shells and sometimes even mother of pearl. These are collected and put to a number of uses. In funnel-shaped estuaries, the tidal wave travels up rapidly and makes it possible for ships to travel further up. 
Tidal waves help to keep the channel free from silt and mud. This makes the sea-port useable for the ships and the boats. Big cities situated on the sea-side dump their garbage on the coast, to be w'ashed away by the high tide.