Selects: How Ocean Currents Work

All right, everyone, Charles W. Chuck Bryant.

Here on a wonderful sunny Saturday afternoon, everywhere I can forecast into the future and guarantee that wherever you are right now, it is a lovely, wonderful Saturday afternoon. This one harkens back to June fourth, twenty fifteen, which was also a lovely sunny day, but probably just a Tuesday or a Thursday. This one is how ocean currents work, and it was super fascinating.

Never knew anything about.

It, and now I do, and now you do too.

Welcome to Stuff You Should Know. A production of iHeartRadio. Hey, and welcome to the podcast. I'm Josh Clark with Charles W. Chuck Bryant, and Jerry And this is stuff you should know, the one about ocean currents.

We should start titling our episodes like Friends did.

Yeah, the one where Ross talks about ocean current Yeah, the.

One where Chuck's eyes glazed over.

I love this stuff, man, Yeah, Like Earth's science really gets me jazzed. That's good, it really does. Like it's so like it's very detailed.

Yeah, there's a lot to it.

It's often oversimplified, but it's also very understandable, and when you really like learn about it, you realize what an elegant system the whole thing is. Sure, maybe not necessarily a living organism, but I could see how someone would characterize it as such.

Yeah, I like that. It's good intro.

That's what I got.

So, yes, title ocean currents, well, not title, that's part of the ocean currency.

It's a type of current. Yeah, it's under the current umbrella.

I've misspoken in the first ten seconds.

I think it's funny that in this article the word current refers to the motion of water when speaking of water.

Is that what it says?

Yeah, speaking of water. Yea, the word current refers to the motion of the water.

Yeah.

Yeah, that was a little clumsy Miriam's defines.

Yeah, well, this is about ocean currents. There are all kinds of currents, river currents, yeah, you know, there's currents in marshes and swamps and currents all over the place.

But this is about ocean currents.

Yeah, as long as water's not stagnant, there's currents present.

Yeah.

If it's stagnant, it's bad news. Jack mosquitoes disease.

Sure, but then again, junk you can make the case that if it's not stagnant, if there's a current, it'll carry your car away in the blink of an eye. Don't even think about it.

Boy, did you see the photos of the Downtown Connector the other day in Atlanta when it flooded. No, apparently the storm drains backed up in the downtown Connector of Atlanta was a lake.

Wow, Like it literally stopped traffic.

I can believe that. Yeah, people in Atlanta don't know how to drive in the rain to begin with.

Oh, I don't know about that really. Yeah, that's all we do is driving the rain. Man, people in La don't drive in the rain.

Seems to me like everybody's brain just drops a couple of years when rain starts, and everyone starts like bumping into everybody else and like driving it two miles an hour and.

You just like pedal through the metal. Yeah, what's different?

All the time? I got good tires.

Yeah, looks as you like tire stores.

I don't like tires stores, but I'm willing to spend time there to get good tires.

Yeah.

That move water away from my car so I can drive really fast no matter what the weather.

You should start your retireble on.

I want to point out Jerry just sighed heavily at this tangent.

I think your retirement business should be Josh's Tire House Emporium. Yeah, and then have a really sweet setup. We'd be like buying tires here is like no place else on earth.

Oh yeah, you got Wi Fi. You got a coffee machine.

Well there's coffee.

Well, no, I mean resta.

Oh gotcha, like a you know, a little mini Starbucks right there in your tires. Sure, games have icebreakers, meet and greets.

Yeah, I could serve icebreakers, gum too.

You have tender tender day.

Okay, you know else, I don't know, that's all I got. Aroma therapy would be good.

Yeah, it would be a big one massage.

Yeah, all right, that's my it's my plan. B all right, Josh's tire Warehouse and Porium, I think is what we came up with.

Sure, Josh's big House of tires or house of big tires.

Okay, So ocean currents, we're back to it. So one of the things that I did not realize, Chuck, when researching this is that ocean currents they're they're old, but there they aren't permanent. They haven't always been around. Yeah, currents change, you know, some currents have been at it for thousands and thousands of years. Other currents change months

Yeah.

I think what I found the most interesting was that ocean currents they have a purpose. You know, it's not just like water moving around willy nilly. You know, if it wasn't for ocean currents, there would be no life in Antarctica. Well maybe not all of Antarctica, but no ocean marine life.

They make that possible.

But that's an important point. Like if there's no ocean marine life, then there's no like say there's no fido plankton. Sure, there's no fital plankton. There's no fishies eating the fyto plankton. There's no fishies around to eat the fyto plankton. There's no seals to eat the fishies. If there's no seals, like everything finds its support, its basis in that ocean life. Absolutely, that's all supported by the currents.

That's right.

So the fact that as purpose, it's very teleological of you, chuck, thank you. So let's not put this off any longer. Let's talk about different types of currents.

You can't talk about tire stores anymore.

No, Okay, we're done with the tire stores. Like I started to get nauseated just talking that much about tire stores.

Oh really, all right, I don't feel good.

Well let's start with surface currents then, buddy, I'll bring you back to the ocean. Earth science, your home, Earth sciences that you love. Surface currents occur about three to four hundred meters deep and above.

That.

Yeah, they're called surface.

Currents, right, and they're driven by the wind.

Yeah.

They make up for about ten percent of the ocean. And if you've ever gone to the beach, you've seen coastal currents.

Surface currents. There's a couple of types. Coastal is one of them.

You've seen them in action, right, like playing in the sand as a little kid or as an adult. You're seeing coastal surface currents at work.

Right.

So let's step back one more degree. So service. Currents are created by wave.

Action, that's right.

Especially coastal currents are created by wave action, which is created by wind. Waves are created by wind. And you know Buckminster Fuller, the inventor of the geodesic dome, among other great things. Sure he was the person who pointed out that the wind doesn't blow, the wind sucks. That's a good point, right, So and so if coastal currents

Yeah, Like if you've again, if you've ever been to the beach and you see the tide or the waves coming in at that angle, and you see it moving with the beach, Like if you've ever been out playing on like a raft as a little kid, you look up an hour later and your parents are like half a mile down the beach from where you start, right. It's a bit of a panicky situation.

It is. And also you're like, what kind of parents do I have that they just let me drift half a mile?

Yeah, you know, they're passed out in the sand at that point.

Yeah.

So that is called.

When a wave breaks on the beach at that angle, it's gonna pull sediment and sand and water down in what's known as a long shore current. That is it's directed off parallel, also perpendicular, but the parallel movement is the long shore current.

Yeah. It's like when a wave comes in in an angle to the shore, Yep, it distributes its energy, part of it directly onto the shore, part of it parallel to the shore. That's that long short current, like you said, and one of the things that it does you also said, is it takes that sand and other stuff and deposits it elsewhere further down and along the way. It creates things like barrier islands and sand bars and all that stuff.

Yeah, that's the long shore drift.

And like, if you've ever seen like the beach curve back end pretty hard. The water can't make that turn really, so it's just gonna deposit stuff and sort of drop it off there at the end of that point, and it'll build up in what's known as a.

Spit, right, And so yeah, all those obstructions, all of those deposits form obstructions for waves when they're going back out. Once they transfer their energy, they're like, oh, I'm pretty far inland. I need to get back out the ocean. And so it backs up right, and as it does, it encounters these underwater barriers that it itself have deposited. It's kind of a big ironic moment, and so it can't get back out to see as fast as it

Yeah, like, hey, look at that little narrow channel. I'm gonna take all this water that would normally just flow out and I and easy, I'm going to send it through there, and I'm gonna grab your little kid and take it, take them.

With me, right this It creates basically suction, just like when you open a drain in a bathtub and it starts to drain, it drains pretty quick.

Yeah, it's dangerous, like that's how you drown when you're swimming in the ocean.

Right.

You hear about strong rip currents and inclement weather, and it's no joke. Even really good swimmers can get caught in a rip. Oh yeah, And it's bad news.

Riptide, very bad news. Yeah. And then there's some other currents that are created that don't just occur at the at the shore, but they do. They occur in the ocean and at the shore. Yeah, there's this thing called upwelling. Yeah, like this stuff and upwelling can happen in a few different ways, but as far as the coast is concerned, when wind comes in and it basically blows water away from an area, yeah, like from the shore, right, water

Yeah.

It's another like what strikes me when you look at wind and all these currents, everything is circular almost.

Right, so a lot of spinning going on.

Yeah, there's a really distinct relationship between wind and water. It's inseparable, especially when you're talking about global winds and currents together, right, Yeah, but both of them are broken down to fluid dynamics, and they do form these circles and cycles and clockwise motions and counterclockwise motions depending on where you are in the world.

Yeah, And in the case of upwelling and down welling, it's not a horizontal spin, but it is a vertical from top to bottom and then from bottom back up to the top.

Yeah, and you want to talk about that was which one.

Well both, it's the same pattern from top to bottom and bottom to top with upwelling and down welling.

Right. And the whole thing about upwelling and down welling, whether it's at the shore or in the ocean, is that the ocean is kind of It's not like if you take a slice of ocean at the top and you take a slice of ocean at the bottom, very different and you look at them, yeah, under a microscope or test them for whatever, you know, using some sort of spectroscope, maybe some sort of oscillate or glavin or

Yeah, And with upwelling, like I mentioned earlier in Antarctica where it's super cold and you would not expect marine life to do so well, it is because of the upwelling that brings the nutrients from the bottom up to the top.

Yep, and that cycle and that's called life.

And one other really neat thing about upwelling and downwelling is the oxygen that's at the top of the ocean. Were it to just sit there for very long and dissolve, we would have a very big problem because all of that life, once it dies, would decay very quickly up top.

Yeah that's not good.

No, it wouldn't because anaerobic bacteria would begin to thrive and we'd have a overabundance of hydrogen sulfide, which would lead to ocean acidification, which would mean the end of the world basically.

Yeah, So that nutrient swap is very important for everybody on the planet.

Yep. And there's this elegant solution to the oceans that happens every day everywhere in the ocean thanks to upwelling and downwelling.

All right, well it's a good start, my friend. My eyes are not glazed over. Actually good, they're sharp, full of life. We will talk after this break about some more surface currents. All right, Josh, there's more than one kind of surface current. We covered the I kind of like that first part, but there's also surface ocean currents.

Yeah.

And again the wind is the big contribute to how these babies form, and specifically, I guess we should talk about the Coriolis effect.

Yeah, this is a this is a game changer, as people who read self help books on airplanes would call it. Right. So yeah, so again, it all starts with heat, and all that heat is found in its thickest part at the equator. And my brain is broken. So at the equator it's the hottest, right.

That's right. And it's also also spinning faster at the equator than at.

The poles, right it is, Okay, So it's the Earth that is Yeah, So at the equator it's hot, it's spinning faster because of the spin. Because of the heat. The ocean is actually about eight centimeters high, higher here than at the rest of the ocean.

Yeah, that's so much higher.

So there's a right, it's just enough to make water flow away from the equator. Now, plus you've got wind that's whipped up because hot air at the equator starts moving northward and cools down and that creates wind. Right, So if the Earth didn't rotate, you would still have these things, but wind would travel in a straight line away from the equator toward the poles, cool down and turn around and come back in a straight line.

That's right. But that's not the case.

No, it isn't because the Earth does rotate and it produces the Coriolis effect.

Yeah, it's like a curve.

Basically, it curves to the right and the northern hemisphere and to the left in the southern hemisphere.

Right, So it makes wind curve, and since wind drives surface currents, it makes surface currents curve as well. Right, that's right. So what's really cool is the ocean has its own topography. Oh yeah, it's definitely not flat. Anybody who's looked at it ice, you could be like, oh,

Yeah.

So, like I said, it has its own topography. And this is created by those winds that push on the water. And as they're pushing the water up and the Coriolis effect is turning it, some water starts to kind of mound. So in some parts of the ocean you have water that forms a mound that's about like three to six feet tall.

Yeah. It doesn't sound intuitive, No, I don't water mounting up on itself.

You think of it as flat. Yeah, but there is actually water that's mounded up into little hills. Yeah okay. And so that means that gravity wants to push this water downward, right, But it doesn't just go back down the hill, because the Coriolis effect pushes it upward. And the net outcome is that instead the water just says, how about it just go around instead? Yeah, you stay up here on the mound, you stay down here. But

That's right, g y r e s and they are the North Atlantic, South Atlantic, North Pacific, South Pacific, and then the Indian Ocean has its very own gyre. Yes, there were smaller ones around Antarctica, but those are the five major gyres.

We talked about the Gulf Stream earlier.

That is a part of the North Atlantic gyre, and it carries forty five hundred times the water of the entire Mississippi River.

Yeah, the Gulf Stream does.

Yeah, the Gulf Stream is.

The hero of all gyres.

It is it moves. Let me see, I've got to find this one because this is so amazing. So the Gulf Stream, at any given point, it moves water at a rate of fifteen superdomes worth per second. So you remember the superdome in Louisiana. Yes, sure, say you filled it with water, okay, and then you took that but copied it fifteen fourteen more times h So you have fifteen super domes full of water. That's how much water

How many big max is that it's trillions of big macs, billions and billions served.

But the Gulf Stream itself is actually it's technically the western boundary current of the North Atlantic Gyre.

Yeah, and it's going to carry warm water. It has a big impact in the world.

It's gonna carry warm water up north from the Gulf of Mexico. And that's why if you're living on the east coast of Florida, you're gonna have cooler summers and warmer winters. Western Europe is going to be a lot warm than other places on its exact same latitude. And this is all because of the Gulf Stream.

Right.

You can deposit bodies in it if you're a dexter. Yeah, and those things are gonna yep, see a later body.

Yeah, it'll probably get carried to England and they'll be like blind, he what was this? So that's just the Gulf Stream. There's actually at least four major currents that form the boundary currents of the North Atlantic Gyre. Yeah, and then the North Atlantic Gyre is just one. We've also talked about gyres before with the Great Pacific garbage Patch.

Yeah, we covered did we do waves or did we just do We did waves.

We did rogue waves too, but we covered waves and surfing.

Okay, yeah, yeah, yeah, remember that.

But these these boundary currents are created again in part by the winds flowing away from the equator, the Coriolis effect, turning the waves and the mounds of water circulating the waves in it around them.

Yeah.

So you've got these like just clockwise or counterclock depending on which hems for you, are currents that are just massive that move water around and again they cycle nutrients. Like you said, they affect the weather, yeah, because they deposit warm water from the south up to all the way up to England apparently. So you know, England is on the same latitude as like some glacial parts of Canada. Yeah, that makes sense, but their winners are like nothing compared

Thank you Gulf Stream.

And if you want to thank the Gulf Stream, Chuck, you can thank Ben Franklin because he's the one who named it.

Oh really.

Yeah. As the first Postmaster General of the United States, he wanted to figure out why mail took so many more weeks longer to get from England to the US than it did from the US to England.

Because they're going against traffic exactly.

But he didn't know that, and he found out and he took some measurements and roughly charted the golf stream back in the eighteenth century.

Man, he was a smart dude, he really was. That's pretty amazing. Yeah, I didn't know he dabbled in oceanography.

But again, the golf stream amazing. And it's just one boundary current of one major gyre.

Yeah, it's kind of a hypnotic if you look at these motion maps of global motion maps of like trade winds and ocean currents.

Yeah, I could watch those videos all day.

Yeah, it's just stuff spinning around and like traveling around, and it's really it's soothing.

And especially when they do like heat gradients or topographical gradients. So it's really colorful too, and it's ever shifting. Oh yeah, you can just get a little jewel out of the corner of my mouth when I watch though.

It's about as good as watching Fantasia.

There's one other thing we should say about those surf currents is they drag on the water below them, right, So the wind is transferring its energy to the surface of the water.

Yeah, and it drags a little bit less is the deeper you go, right?

Apparently though the current that the motion of water usually goes in opposition to the motion of wind. So what you end up having if you could take a column slice from top to bottom of the ocean, you would find that the water ultimately is making a very long downward spiral. Yeah, and that's called the Ekman spiral.

Yeah.

That there's a graphic of that that looks pretty neat as well, pretty neat again, mesmerizing stuff, So Chuck.

After this we will talk about the global conveyor belt.

That's my favorite part, I think, okay, Ken, all right, my favorite part of ocean currency ocean currents. It works the deep ocean current aka the global conveyor belt.

It is fascinating to me.

If you're talking about this is about ninety percent, if the surface currents are about ten percent, about ninety percent of the ocean's water is part of the deep ocean current, and we can't see it because we're up here on Earth and we are not deep under the water. It's invisible to us, right, But it circles the globe at afore sixteen times as strong as all of the world's rivers combined.

Which is again still not as much as the the Gulf Stream. Yeah, still pretty impressive.

It's pretty impressive. Yeah, but it's slow, so like water.

It moves super water a few centimeters a second, whereas the Gulf Stream moves waters at like a couple hundred centimeters a second.

Yeah.

I think the conveyor belt, they said, like one patch will take a thousand years to completely around, yeah, the circuit.

Yeah, and it takes ten years for water to make a full circuit on the North Atlantic Gyre.

Yeah, so ten years yeah, and then a thousand years right wow. Yeah, So the global conveyor belt, it is driven by density, which I think is pretty interesting.

Yeah, because up to this point it's all been driven by wind, which is ultimately driven by heat. This is also driven by heat in a way, but in a completely different way.

Yeah, heat and salt thermohaline circulation, the thermo being heat and haleine being salt.

Warm water holds less salt.

So what happens is like, let's say you're in the Antarctic and water freezes to form an iceberg or water evaporates either way, salt is not going to be a part of that equation.

No, the salt is left behind as Yeah, water freezes, and you know icebergs aren't salty their fresh water.

Yeah, so the salt is left behind. It's got to go somewhere. It is going to be very dense at that point. So it is going to be cold and dense and sink to the ocean floor.

Right. So remember back when we're talking about right, and we were talking about coastal coastal currents and up welling and down welling.

Yeah, this plays a part.

When water sinks, other water moves in to replace it. And so what starts off here and this actually I think starts around the North Pole definitely in the North Atlantic. As that water sinks and moves downward, it creates. It starts this current that goes all the way around the world and again takes a thousand years to complete.

Yeah, it just kick starts it basically.

And it's called the conveyor belt, I think because it never stops moving and it's super slow.

Yeah. I kept getting that, remember that whatever that Bugs Bunny assembly line song? Like it was always the same.

Like, dude, don't remember that.

I can't remember it either. Now I have our theme song in my head. I'm trying to think about it. But there's like anytime Bugs Bunny messed around on a conveyor bell or something, they use the same like composition.

Oh really, yeah, I'll try to find it all right.

So, once this water hits Antarctica, basically the same thing happens all over again. The cold water is gonna split. Some of it heads to the Indian Ocean, some heads to the Pacific, and this upwelling and down welling, this cycle just starts all over again.

Yeah. As it moves closer to like the Indian Ocean and the Pacific, it gets closer to the equator, the water starts to warm up, it loses some of its salinity, it starts to thin out a little bit, and so it rises, and when it does, it takes all those nutrients and all that CO two up with it. And it's very much like the gas exchange that occurs in the human cardio pulmonary system. Right.

Yeah, it's not homeostasis, but it almost feels like that.

If you took the whole system overall. Yeah, it's homeostatic for sure, but it's like that by this exchange, this transfer from one part to another, from the deep ocean to the surface. And this as it reaches the surface and it depletes its nutrients, it's carried back around. It basically tries to go up hits Alaska, Russia, Asia, North Asia, Northeast Asia, and turns back around and goes ends up finally back in the North Atlantic, up near the North Pole.

And gets cold and starts all over.

Right, And by the time it gets there, it's basically nutrient depleted and it sinks and it starts to recharge again.

That's right in that just like blood.

In your in your cardiopulmonary system, it gets depleted, it ends up going past the lungs, it transfers out CO two, it gets in oxygen. This is just the opposite. This is transferring out oxygen and gaining CO two and nutrients.

Way to feel connected to the Earth when you start looking at things like that, you know, yeah, it's not so different.

It's I mean, we're all connected, man.

And again there's a big nutrient swap meat happening as well with the conveyor belt like we're talking about, and basically kind of has the same effect as those surface currents do. Yeah, as far as exchanging the oxygen and the CO two and nutrients and just moving everything where it needs to be.

I thought this was pretty cool. In this article it talks about there's also a density driven to Thermohalian current in the Mediterranean because the Mediterranean is apparently saltier than the Atlantic, and as a result this gradient. Anytime you have a difference in something, whether it's height, temperature, salinity, density, homeostasis is the ultimate goal, so it's going to try to go toward the middle, from higher to lower. Yeah, and this is the same thing. So it creates that

Oh really, Yeah, so they would run like a glider. Deep run, silent run deep exactly. Wow, that's frightening. All right. Are we at tidal currents?

You don't have to be frightened. It was years ago. Yeah, we're at tidal currents.

I think they still do that.

No, there's no submarines anymore. We haven't been at war for years.

They retired all the submarines.

Yeah, all right. Tidal currents are generated by the tides. We did talk about, like we said, I think in the Rugue waves and surfing about tides and waves.

Yeah, and.

The gravitational pull of the Moon and the Sun, but more of the Moon because the Moon is closer, Yeah, is what's gonna cause that bulge on the sides, and it's going to drive the water level at that bulge. Basically, it's going to decrease. It's going to increase where it's aligned with the moon and decrease at the halfway point between those two places.

Right, and so, And it's always changing because the moon, the position of the Moon and the Sun and the Earth are always changing, but they change in a very predictable manner. So we can predict when the tides happen. But if you just took a snapshot at any given

That does something for you.

Does it all the way?

And these are different than the other currents who talked about because they're not it's not a continuous stream and they switch directions. That's the high tide and low tide and it doesn't impact like the ocean.

Current that much. It's shoreline stuff.

Yeah, but it's pretty important. I mean, like fish, fishes lay eggs, and sure low tide will pull those eggs out into the open ocean and those fitch they'll hatch.

Yeah.

It also brings food in from the ocean into like marshland that kind.

Of stuff, yeah, or washes up jellyfish yep. And to delight the children on the beach.

Yes, but don't touch them. You can just look.

And when the tide is rising, that flow is directed toward the store.

That's called the flood current.

We've heard about that flood and the EBB, and the EBB is when it's directed back out to sea.

That's right, and that makes it all very predictable.

Like you said, we can go to the beach and listen to the tide report.

That's also a very relaxing thing to do.

Oh yeah, oh yeah, listen to that like the am like fishing and charts and tidle reports.

Yeah, it's very relaxing for me.

I like it. I remember growing up listening to like grain future reports and hog reports.

Oh really like that. Pork bellies, yeah, pork futures.

Yeah, chuck, just a couple more things. So, like, there are plenty of other currents and there's also plenty of other wind patterns that drive these currents. They do things like create the El Nino, yeah, which basically takes weather, thunderstorms and stuff around the equator and move them in different places that we're not used to, which can lead

Polar bears are upset, well, the poor seals die. Either way, Yeah, it is very sad.

Yeah, you got anything else, No, that's it. That's ocean currents. If you want to know more about ocean currents, you can type those words into the search bar at HowStuffWorks dot com. And since I said search bar, it's time for a listener mail.

I'm gonna call this A French speaker doesn't like our heavy metal music interludes.

There's a few people out there who.

Don't, So here we go. I'm going to read this just as it came. I like you very much. Sorry for my bad English, but I speak French so it compensates.

I have a little problem. I feel like I need to tell you, please.

Don't take it the wrong way. I have had problems to sleep for a while now, and I found that listening to podcasts helped.

Me a lot.

I put my iPod under my pillow while it plays, or I put only one head sound thing in one ear. I love your podcast because it's very interesting, intelligent, and also your voices are nice and you are never yelling, so I do fall asleep every single time. This is a good thing, I swear. Of course, it takes me three or four times to listen to all of it. Usually I relistened to it in the car. Now my problem, why do you have to put loud heavy metal music for a break. I always wake up in panic when

So you have two choices.

Either you don't change your music and think of me every time and laugh, or you change it for something, let's say nicer. Maybe in exchange. I'm sorry, exchange, I could give you pickup lines in French orvoir of Danielle.

I have to say hats off Danielle because I couldn't write that in French.

Oh well, no, you don't speak French, do you?

Mpikito perfect? Thanks a lot, Danielle. We will consider removing the heavy metal music, which we did before and then we brought back because other people are like, bring back the heavy metal music. So we're kind of caught between a rock and a hard place.

Caught between an amp and a hard place.

Yes. If you want to let us know how you feel about our music or anything else, you can tweet to us at sysk podcast. You can join us on Facebook dot com slash stuff you should know. You can send us an email to Stuff Podcast at houstuffworks dot com and it's always joined us at our home on the web, Stuff Youshould Know dot Com Stuff you Should Know is a production of iHeartRadio.

For more podcasts my heart Radio, visit the iHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows.