What Exactly Does ‘High Tide’ and ‘Low Tide’ Mean?

You’ve moved your beach chairs 20 times in the past few hours. It feels like the waves are getting closer and closer, until finally they begin to retract. This is the tide.

Define it

According to the NOAA, “​tides​ are very long-period waves that move through the oceans in response to the forces exerted by the moon and sun.” The moon has a gravitational force on the Earth, so in response to the Earth’s water, this force is the ​tidal force.​ The ​tidal force​ causes the Earth’s water to bulge out on two sides: the side closest to the moon and the side farthest away from the moon.

To the Moon and Back

So we know that the moon causes two bulges, but how does that relate to tidal waves? These two bulges of water are what we know as high tides. When the Earth rotates throughout the day, your region will pass through both of these bulges.
When your region is passing through the bulge, it experiences ​high tide​. Any time your region isn’t in the bulge, it experiences ​low tide.​ Everything that occurs in between is part of the transition from high tide to low tide, which becomes the ebb and flow of the tides.

What about the sun?

The sun is a great ball of fiery gas​⁠—​arguably stronger than the moon​⁠—​so its effect seems to be the missing piece of the puzzle. While the sun isn’t as closely related with tides as the moon is, it still has a distant effect. Remember: The sun is much farther away from the Earth than the moon is, so its effect on our water isn’t as noticeable.


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