What causes tides to occur?

Question

when low tide occur where do you the water go?

Answer 1

Tides are quite complicated, and are caused by the difference in gravitational attraction from one side of a large object (such as the earth) to the other.  

Tides on earth are caused by the gravitational attraction of the earth to the moon and also to the sun.  Although the moon is a lot smaller than the sun, it is a lot closer to the earth; so the moon's gravitational effect on the tides is about three times that of the sun.

The highest tides ocur when the sun, the earth and the moon are all in line, and the gravitational attraction of the sun and the moon is aligned. These are called 'spring tides', and they happen during new moon (when the sun and the moon are on the same side of the Earth), and full moon (when the sun and the moon are opposite each other).  When the sun and the moon are at right angles, relative to the earth (during half moon), the tides are at their weakest, called 'neap tides'.  Also, during its orbit around the sun, the earth is closer to the sun at times; and during these times, the spring tides are at their highest; called 'king tides', ot technically 'perogee syzygy' tides - meaning 'closest in line'.

It is easy to understand why there are spring tides when the sun and the moom are on the same side and 'pull together'; but spring tide when the sun and the moon are pulling 'against each other' during full moon seems counter-intuitive:

Ignoring the effect of the sun for the time being; we discover that high tides ocurr on opposite sides of the earth at the same time.  This is also difficult to understand; surely if the tide is caused by the gravitational attraction of the moon, it is obvoius that the seas on the side closer to the moon would bulge out towards the moon. Why then, would there be a high tide on the opposite side? - You would think that on the side furthest away from the moon, the effect would be that the tide there should be lower, because of the bulge on the side nearest the moon.

The reason has to do with the fact that gravitational attraction  towards the moon is weaker on the side of the earth facing away from the moon.  In effect,  the seas closer to the moon are attracted towards it, but at the same time, the gravitational centre of the earth is attracted towards the moon MORE than the seas on the furthest side; and so the earth is 'pulled' away from those seas.

The net effect is that the seas closest to the moon are subject to a net pull TOWARDS the moon (relative to the earth), and the seas on the opposite side are subject to a net pull AWAY from the moon (relative to the earth).

Now bringing the sun into the equation, we can see why tides are highest at full moon:  Then, the seas facing away from the moon are pulled AWAY from the moon relaive the the earth; but at the same time are pulled TOWARDS the sun, relative to the earth.  The effect is reversed on the side facing the moon: net attraction TOWARDS the moon and AWAY from the sun.

Now it can be seen why tides are highest at full moon.

The effect is called tidal stretching, and is caused by the fact that gravitational attraction between two bodies decreases with the square of the distance between them. This has startling effects near very strong gravitational objects (the most powerful being a black hole) An object falling into a black hole would be infinitely stretched, because of the tidal effect.

Answer 2

Due to the gravitational effect of the moon, water on earth slides towards the equator and "peels" off.  It is then sent on an path of inter-orbital pressure, does one loop around the moon and returns about 12 hours later.

Answer 3

gravity.. take an english lesson

Answer 4

the gravitational pull from the moon.

Answer 5

The moon's pull on the Earth. The water doesn't really go anywhere...the water just becomes 'deeper' at another point of the ocean further out.

Answer 6

Gravitational pull of the moon causes the tides to occur.The high tide occurs both in the direction of the moon and on the opposite side of the earth.Low tides occur approximately 90 degrees(on both sides) from the direction of the high tides.The water does not go anywhere.It piles up in the direction where high tides occur and decreases by the same amount over the places wher the low tides occur.