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What Causes Ocean Tides?

Ocean Tides Moon Effects

What Causes Ocean Tides?

If you live close to the coast, you probably know that water hits a high and low level throughout the day.

When water is at its maximum height, then it’s high tide. But when water is at its lowest height, it’s low tide.

High tide usually lasts about 6 hours. And it’s generally the same for low tide. Also, tides hit a high and low usually twice a day.

But what causes tides? And why are there low and high tides?

The effects of the moon on ocean tides

Ocean Tides

The main reason that causes ocean tides is the gravitational attraction between the moon and Earth:

  • HIGH TIDE: When the moon is close to the Earth, it stretches the side of the planet that it’s facing. The side that is closest to the moon has a high tide because the moon pulls the body of water close to it.
  • LOW TIDE: The side farthest away from the moon has a low tide because the gravitational force is weaker and doesn’t bulge out.

As the Earth rotates, the bulge shifts to the side facing the moon. But because oceans hold a set amount of water, water levels rise in one area and drop in another area. This is when there are high and low ocean tides.

Our enormous sun, which holds 99.9% of the total mass of the solar system, has an effect on the ocean tides as well. But it’s not as strong as the moon because the sun is farther in distance.

What Causes Ocean Tides?

When you think of the ocean, you often think of waves and water. But did you know that there is another force in the ocean? The tides are caused by the gravitational pull of the moon and sun in relation to Earth.

That’s right. Ocean tides are primarily caused by the gravitational pull of the moon and the sun on Earth’s oceans.

As the moon orbits the Earth and the Earth-moon system rotates around the sun, the varying gravitational forces lead to the rising and falling of ocean water levels, creating the daily tidal cycle.

Do you have any questions or comments about ocean tides? Please use the comment form below and let us know what’s on your mind.

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  1. Wow, this is so well explained. I love it… But can you please go deeper by what it means to cause ocean tides. Thanks

  2. Your explanation of high and low tides is incorrect. There are two ocean bulges that cause two high tides and two low tides per day as the earth rotates through each ocean bulge and not as you describe. The ocean bulge nearest the moon is caused by the moon’s gravity and the ocean bulge on the opposite side of the earth is caused by the earth-moon system’s centrifugal force (not withstanding spring and neap tides). Each ocean bulge is of equal size because of the earth-moon system: the force of gravity and centrifugal force are perfectly in balance as a result of the earth and moon rotating about a common center. They have to be otherwise the earth and moon would not stay in this orbit.
    Best wishes,
    Andy Brownen.

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