Q:

Why do tides occur?

A:

Quick Answer

Tides are caused by a combination of three factors: the moon's gravity, the sun's gravity and the earth's own gravity. The moon's gravity is the most significant of these forces; it exerts 2.2 times more force on the tides than the sun's gravity does.

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Full Answer

Lunar and solar tides occur in regular cycles. Lunar tides occur over a 24 hour and 50 minute cycle, while solar tides occur over a 24 hour cycle. In addition to these daily high- and low-tide cycles, the monthly lunar cycle produces what are called spring tides and neap tides.

Spring tides occur at the new moon and the full moon. All three gravitation forces that cause the tides are aligned at spring tide, causing a greater than average difference between high and low tides. Neap tides occur at the half moon and three-quarters moon; at neap tide, the sun and moon are 90 degrees apart. Their gravitational forces work against each other, causing a smaller than average difference between high and low tides.

The world's smallest tidal distances occur in the Mediterranean Sea, where the difference between high and low tide is less than 3 feet. The greatest distances are found in the Bay of Fundy in Canada, where the difference can exceed 50 feet.

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Related Questions

  • Q:

    What causes neap tides?

    A:

    All tides, including the cycle of spring and neap tides, are caused by the gravitational pull of the sun and moon on Earth's ocean tides. Each month, the angles and alignment of the sun, moon and Earth work to influence the cycle of tides.

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  • Q:

    Why are there tides?

    A:

    Tides form when the gravitational forces of the moon and sun act on the Earth as it spins around its axis. Tides are the rise and fall of the sea level in reference to land. For example, spring tides are the result of the alignment of the sun, moon and Earth that typically occurs during new and full moons.

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  • Q:

    What are high tides and low tides?

    A:

    Low tides and high tides occur as a result of gravitational forces between the moon and Earth. There is a gravitational force exerted on every object on the planet by the moon. The effect of the gravitational force is more apparent on bodies of water than it is on land.

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  • Q:

    What are lunar tides?

    A:

    According to Science and the Sea, lunar tides are the most common tides and are caused by the Moon's gravity. Although the Sun's gravity is stronger, it is farther from the Earth than the Moon, which is why lunar tides are more than two times stronger than solar tides.

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