Where does seawater go when it’s low tide?
In: Physics
Did you ever see interstellar? [This](https://www.youtube.com/watch?v=4Hf_XkgE1d0) scene in particular. In this scene the black hole near the planet is pulling all the water up towards in giant swells of water, which leaves only a little water between the swells.
Same thing is happening on earth. The moon pulls, the water rises towards it. So the water is basically going into big swells that move back and forth. Luckily the moon is a lot smaller so its gravity is much weaker, and we dont have to deal with that nightmare fuel.
There’s a lot more to it, and this is very over simplified, but that should get you started anyway.
To the part of the ocean right underneath the moon. There’s a bulge of seawater right there due to gravity
(There’s also a second bulge on the opposite side of the planet from the moon, but that one’s a little more confusing to think about. It basically means the same thing for tides though.)
It goes to where it’s high tide.
At any given moment there’s two high tides and two low tides around the world. The moon pulls the oceans outward on the side facing the moon and the side facing away from the moon on the opposite side. The reason you’re having a low tide is *because* there’s a high tide 90 degrees longitude to your east and another one 90 degrees longitude to your west. Those two high tides are stealing your water. But don’t worry, 6 hours later you’ll be at the high tide spot 90 degrees to your east and you’ll be the one stealing water from them.
And it’s not just the water. It’s everything. If you had a super sensitive scale, you’d look like you weigh slightly more at low tide than at high tide. It’s just that ocean water, because there’s so much of it, makes the effect of that slight change more obvious.
It’s not where the water goes, it’s where you go. The gravity of the sun – as we understand it – pulls the water harder in one direction, creates more depth there. But that’s a really slow process, 30 days per revolution. Meanwhile, we are spinning inside that shape every 24 hours and the single point where you are standing sees a rising and falling tide.
Almost every answer here is somewhat misleading, with regard to your actual question about where the water goes. The water doesn’t travel to the spots with the opposite tide, to do that it would have to travel hundreds, even thousands of miles per hour. The actual coastal water goes offshore a few miles. I’ve watched small boats and debris go out with the tide and come back in with it for decades. Anyone who lives by the sea is accustomed to that process.
The earth has love handles made of water, they rotate around the planet with the moon, when it’s high tide in a place a love handle is present, at low tide there isn’t one
Think of it this way,
When you move from one place to another, you are no longer in the place you were before.
This is what water does, it moves from one place to another
Think of it like tug of war. You’ve got one end of a rope, I’ve got the other end. If I pull the rope hard, you have less, I have more. If you pull hard, you have more, I have less.
The sea is no difference. High Tide here basically means low tide on the other side of the sea. Low Tide here means High Tide on the other side. In larger seas/oceans this may take some time because of the big distance, but the sea is just sloshing back and forth between coastlines.
Imagine tugging/pinching up on a sheet that’s on a bed. Your hand is the moon, the height of the sheet is the water level. It’s high tide where your hand is.
Now let go and pinch up somewhere else on the sheet. That area is high tide, the other area is now low tide.
The high point travels in relation to where the moon is vs the earth’s seas.
If you have access to a second hand, press up from underneath the sheet with your palm. That’s the effect from the sun. Occasionally, the two can combine or be opposite, and since water is limited, that can result in higher or lower tides.
Note: someone else could likely improve upon this a lot. Hopefully it’s a nice start.
To be even more accurate, my understanding is that the water doesn’t actually go anywhere. It’s the earth that moves under the bodies of water that are being held up slightly by the gravity of both the moon and the sun.
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