How does the tide increase/decrease the water level when the net amount of water stays the same?

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How does the tide increase/decrease the water level when the net amount of water stays the same?

In: Physics

The moon’s gravity causes the tide rise and fall. As it move around the earth it pushes and pulls the water. The pushing effect, or high tide, is just water displacement. The earth ocean is usually in the shape of an oval figuratively speaking.

If you’re interested in a bit more of a specific explanation than just “the moon’s gravity causes the water on Earth to have an oval shape” (which is true) then take a look at this video. PBS Spacetime has lots of great videos like this one – https://youtu.be/pwChk4S99i4

The more interesting question is why don’t you notice tides in smaller bodies of water, like lakes or pools? The answer is really interesting, so the explanation is that the moon’s gravity causes it is right but incomplete. The water isn’t ‘pulled’ up so much as the top bit of water throughout the oceans is pushed in one direction, you don’t notice it in open water but when you get to the shores all of that water creates a tidal wave of water that has accumulated due tot his effect. There is a picture running about that leaves the impression that the moon’s gravity is capable of actually pulling the water up, the gravitational effect is nowhere near that strong. And if it were, you would notice the effect on other bodies of water. The explanation is essentially correct it *is* gravity, the mechanics, as they are popularly explained, is generally wrong.

Tide rises in some parts of the world, falls in others at the same time. Fill a baking pan with 1″ of water. Now tilt it slightly, it’s more than 1″ on one end and less than 1″ on the other end… similar idea

The tide does not reflect the total volume of water available — just how much of it is pushed up on a particular shoreline by the influence of the moon’s gravity and prevailing winds, etc.