Earth's tides. How the moons gravity and other factors affects this natural pattern.

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Earth's Tides

Gravity is the key to the Earth's rising and falling tides. The combined

gravitational effects of the Sun and the Moon constantly pull the world's oceans

in different directions and create tidal effects. But there are several other

factors that complicate this basic process. Friction, the Earth's rotation, the

tilt of its axis and the gravitational pull given off by the Sun and Moon that

affects Earth's atmosphere. These forces together conspire to make our planet's

oceans into a battleground. These forces tug the oceans this way and that way

around the globe, thus creating high tides and low tides.

The Moon's gravity stretches the earth into an oval. The effect is so tiny

that the solid parts of the planet are distorted by little more than eight

inches. But because of of water's fluidity, the effect on the oceans is more

noticeable. At the point on the Earth directly beneath the Moon, the ocean is

tugged into a bulge of high water.

At the same time, a second tidal bulge forms

on the opposite side of the planet. This is partly a result of the centrifugal

force created by the Moon and Earth's combined rotation around their common

center of mass, a theoretical point called the barycenter.

Because the Earth spins on its axis once every 24 hours, the two bulges sweep

around the planet in waves, creating two high tides per day at every point on

the globe. But the twice daily cycle is complicated by he fact that the Earth

is tilted, which puts the Moon alternately to the north and south of the

equator. This creates slight differences between the two tide each day and adds

a daily set of local variations to this natural rhythm.

A further complication is added by the Sun,