A community for a webcomic of romance, sarcasm, math, and language.
Title text:
They're up there with coral islands, lightning, and caterpillars turning into butterflies.
Transcript:
Transcript will show once it’s been added to explainxkcd.com
Source: https://xkcd.com/3135/
Everyone was taught the tides look like two giant water bulges going around the earth in line with the moon.
That representation is oversimplified and false.
This is how the tides look like at a global level. It’s messed up.
Ok, that clarifies things so much better for me. Thank you.
You understand it more after that?
I'm more confused, honestly. But that's hardly surprising.
The pictures they used to teach us the tides as children came to make less sense to me in regards to certain places having higher tides than others. I couldn't picture how. That animation clarified how tides are ordered by the Moon and made chaotic by the shapes of land. The planetary ocean bulges they taught us as kids stuck with me too long and prevented deeper understanding. It finally clicked for me.
Fair enough.
I just have a hard time translating what what shown in the video to what's actually happening. Might be a bit too much to take in at once.
Then again, I haven't cared much about the tides ever, and I only know that the tides are a function of the moon because of Bill Nye, I think.
My HS "education" was pretty bad, honestly.
Look at one spot and see how it repeats. Like the tides between South America and Africa kind of rotates through the Atlantic.
Tides in the Bay of Fundy, Canada are 16 metres (50 feet).
See, that's the part that confuses the hell outta me. How can water be higher in one spot than others just due to the Moon's gravity? Yeah it's the geography of the area, got it. But still, how?
Ever seen a ferrofluid, which follows the shape of magnetic fields? Same thing, but with gravity.
Of course, that only accounts for a fraction of those 16 meters... but there's a lot of ocean water. Get it moving (because the Moon and the Sun move, and the Earth rotates under them, and there's a whole lot of ocean currents on top of that, due to differences in water temperatures and salinity, and coriolis forces, and winds, and whatnot) and it builds up a lot of inertia.
Push it into geography that keeps narrowing and narrowing like a funnel, and the only place it can go is in, and up.
Water gets in there, wants to get out, but there's a whole damn ocean pushing it in, so it has no option but to keep accumulating into the funnel.
Also, having the geography look a bit like a Tesla valve that'll easily let water in but not so easily let it out probably doesn't help either; place's bound to get close to overflowing, before it can empty itself out.
"Their moon is tidally locked" is an absolutely metal thing to say about a planet.
I wonder if anyone has ever done the math on how much (in L or kg) water is moved by the moon each day. It's got to be something absurd.
Just wanted to mention I see your pfp on every post.
Thank you for keeping lemmy alive and making like 4% of the total posts. Seeing you post brightens up my day.
No homo.
Let's hope Lemmy grows big enough that I can just be part of the crowd.
I have to assume it's about one moon's worth, divided by the distance squared.
That would be its total pull, not just the water.
We probably can estimate the amount of water that's at a different level from what a moonless Earth would.
We could also say that technically all water is moved somewhat, because gravity is like that.
I think lightning would be crazy to anyone who never experienced a planet with it. Like, "WTF, sometimes your sky does what?"
In the Bay of Fundy, Canada we have the highest tides in the world (53 feet high). It's enough to make some of the tributary rivers flow backward with the rising tide. I've seen it my whole life but it still amazes me to see a harbour completely empty of water with boats sitting on the bottom waiting for the tide to come back in.
I live in an area with sea but almost no tide (although wind direction can have a pretty big effect on water level) and I have always felt that tides are weird man.
Yeah I grew up inland and tides are weird
woah XKCD is still making comics?
There are places in the solar system where the tide rips new mountains up every go around.
I remember never believing my parents when they explained it to me as a kid. Clouds being caused by cigarette smoke was reasonable but the moon pulling out the ocean seemed too outrageous.
Does the moon decrease the air pressure enough for that to matter?