how comes tides in oceans?

Answer 1

You know that the moon orbits the earth. The earth's gravity causes the moon to move in a circular motion around the earth.

The moon also has gravity, however, which pulls on the earth. Earth's movement is deviated by this, just as the moon's movement is deviated by the earth's gravity.

In effect, the moon does not orbit the exact center of the earth. The earth and the moon both orbit a common center of gravity, which lies on a line between their respective centers of mass.

The effect of this is, water on the side of the earth facing the moon is nearer to the moon then the earth/moon common center of gravity, and therefore is more attracted to the moon than the rest of the earth. So it piles up there.

Simultaneously, water on the side of the earth opposite the moon is less attracted to the moon then the rest of the earth.

The earth's motion is being deviated by the moon, remember. This imparts centrifugal force on water opposite the moon, so it piles up on that side too.

Thus you get two high tides a day.

Answer 2

SHORT, SIMPLE ANSWER
Mainly due to the gravity of the moon pulling on the seas and oceans.

MORE ACCURATE LONG ANSWER
There's several factors that affect tides, the most noticable one is the gravitational effect of the moon, everything has gravity but the moon is very close to earth compared to the sun and other planets so it's effects are greter.

The moon rotates around the earth and together these, along with the other planets, rotate around the sun.

When the sun, the earth and the moon are together in a straight line is when the gravitational pull is at it's strongest - the moon takes about 29 days to go round the earth so this effect happens roughly each fortnight - once when the alignment is sun - moon - earth (new moon) and again when the alignment is sun - earth - moon (full moon).

The seas and oceans are so massive that the full gravitational effect of the moon takes a couple of days to peak and it's for this reason that the highest tides occur shortly after a full moon or new moon.

The sun also plays a part but to a lesser extent. The earth takes a year to go round the sun and the path it takes is an elipse - a slightly squashed circle, twice during the year we are closer to the sun and twice we are further away. The times we're nearest the sun are the autumnal and vernal equinoxes (the first days of spring and fall). Being closer to the sun means higher high-tides and lower low-tides and as a result the tides are at the highest and lowest at the start of spring and the start of fall.

When the full or new moon coincides with the vernal or autumnal equinoxes we get exceptionally high tides.

Other more localised factors are wind and air pressure. A strong driving wind will push the seas and oceans along in front of it (called a strom surge). An area of high pressure pushes down on the seas and oceans and displaces the water towards areas of low pressure - the low pressure areas effectively 'suck' the water upwards.

When several of these factors combine there can be catastrophic high tides leading to serious flooding and loss of lives. In 1953 a strom surge claimed over 2000 lives in England and the Netherlands and reclaimed over 2,000 square kilometres (800 square miles) of land.

Answer 3

The word "tides" is a generic term used to define the alternating rise and fall in sea level with respect to the land, produced by the gravitational attraction of the moon and the sun. To a much smaller extent, tides also occur in large lakes, the atmosphere, and within the solid crust of the earth, acted upon by these same gravitational forces of the moon and sun.






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Answer 4

tides comes in ocean because of earthquakes or other hazardous disaster in ocean and as well as by moon's gravitational pull

Answer 5

Due to the moons gravitational pull on the ocean.

Answer 6

pull of the moons gravity on the water

also influenced by wind and the earths rotation with a very slight solar influence - but the above is the correct answer

Answer 7

Due to air,earth's gravity due to it's motion and moon's gravitational influence.

Answer 8

moon pulls the ocean, makin waves and stuff.