Things You Thought You Knew – Head in the Clouds

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Hey, Star Talkians.

I've got another things you thought you knew coming your way.

This time we're looking at twilight, clouds, and coastlines.

But you got to check it out to see how they connect and why.

See you then.

welcome to star talk

your place in the universe where science and pop culture collide

star talk begins right now

chuck yeah i'm gonna tell you about the three twilights uh no no no no i'm sorry i gotta correct you on this one there are four twilights you got twilight Then you got new moon, then you got eclipse, and then you got breaking dawn.

I'm afraid that man can bite me any day.

Okay.

I'm afraid the answer is incorrect.

What?

Astronomically speaking.

Oh.

This is a science show.

Oh, okay.

Astronomical twilight

is a thing.

That is an actual thing.

So, Chuck, I don't know if you know this, but there's three different kinds of twilight.

Clearly, I did not.

Okay.

Oh, wait.

Yes, I do know.

So there's the one in the evening.

And then there's the one in the morning.

And then there's the one

where

Edward takes my heart.

No, that's not correct.

Okay.

I'm sure.

I'm pretty sure it wasn't.

But go ahead.

What are the three?

So, twilight, in any given place on Earth, we rotate in such a way so that the sun dips below your horizon.

Unlike some movies and some court cases and some people who think that the instant the sun sets, it's dark.

Right.

Okay.

Nothing could could be more false than that.

They made this mistake in Back to the Future, when Marty goes back to 1955 and he's driving out from

the barn because he visited the farmer's barn and his DeLorean.

And it is dark at the beginning of the driveway.

And at the end of the driveway, you see sunrise and it's light.

No.

No.

That's not how that works.

All right.

Okay.

In John Wick 4, there's this scene that happens early morning hours.

Yeah.

And he ascends this staircase up to this plateau and it's dark and then the sun rises and then it's light.

Okay.

No.

No.

These people just have never looked up.

Okay.

They think the sun alone, direct sunlight, is their only source of light.

You know what else is lighting things up?

The atmosphere.

Okay.

Okay.

So the sun dips below the horizon.

Light is still illuminating the atmosphere above your head.

Right.

It is still glowing from sunlight.

That's called twilight.

We have a word for that, twilight.

Oh, it's beautiful.

It's beautiful.

It's beautiful.

That's gorgeous.

It is beautiful.

Yeah.

By the way, if we had no atmosphere and the sun went below the horizon, dark.

Dark.

Dark.

Oh, you know, they have that on the moon.

Yes.

Yes.

That's why all of our astronauts landed in the daytime.

That's right.

Okay.

That's a good, because otherwise the lights go out.

Yeah.

Like that.

Yeah.

Okay.

So you can ask, the deeper below your horizon the sun goes,

the higher and higher up the sunlight is hitting.

So the lower atmosphere is more and more in darkness.

Okay.

If it's really far around the other side, there's no light illuminating any part of the air above you.

We call that nighttime, right?

Nighttime.

Very good.

Just want to let you know I'm with you.

All right.

There are three kinds of twilight.

There is civil twilight.

All right.

Hello, I'm Twilight.

So terribly nice to meet you.

Quite frankly, I don't want to offend you in any way possible.

I saw a comedy skit with civil engineers.

Right.

And they're just sitting there offering each other teachers.

After you.

Would you like some?

Would you care for another pinafore?

Oh, my good man.

Please, I wouldn't

civil engineers.

If only civil wars could be that polite.

Oh, wouldn't that be something?

You know, I would kill you, but that would be rather unpleasant, wouldn't it?

A civil war.

It's a civil war.

Let's just play checker.

Exactly.

A civil twilight

is

until the sun is six degrees below the horizon.

Six degrees below the...

So, okay, it's a Kevin Bacon twilight.

That's it.

Oh, six degrees.

Six degrees.

Okay.

There's still some light in the upper atmosphere, still lighting it.

But for practical purposes, for ordinary people, nighttime begins when it's six degrees below.

There you go.

Okay.

Civil twilight.

Civil twilight.

People don't have much need for the sky like other people do.

So civil twilight, six degrees.

Let's keep going.

There's another twilight called nautical Twilight.

Oh, okay.

It's got to be darker than civil twilight for them to use their sextant and their navigate by the stars.

That makes sense.

It makes sense.

So the sun's got to be 12 degrees below the horizon.

Look at that.

Yeah.

And at that point, you start seeing many more stars for you to navigate by.

Okay.

Where six degrees, not so much.

Right, because there's still light in the sky.

There's still a lot of light in the atmosphere above you.

The sky is still glowing blue.

Right.

The blue sky is light from the sun.

Right.

Scattered back to you.

Right.

On the moon, there is no scattered light.

So the sky, daytime sky, is as dark as night.

Black.

Black.

So nautical.

Nautical.

Civil.

They get some more stars to play with.

Okay.

But the astronomers,

we go deeper than what the eye can see.

Right.

We bring out telescopes.

I don't want twilight messing with my telescopic views of the night sky.

So we go an extra six degrees lower than nautical twilight.

Wow.

Eight

degrees

below the horizon.

Okay.

Only then

is the end of astronomical twilight.

Wow.

Yeah.

And

what time would that be about?

Well, no, so it depends.

If you're near the equator,

the angle that the sun sets to the horizon is almost vertical.

Right.

So if you're going vertically down, you're booking into the darkness, okay?

Twilight lasts like 15 minutes.

I mean, have you ever been in the Caribbean?

There is no culture of twilight in the Caribbean.

That's true.

Okay.

Yeah.

It's light and then it's dark, not instantaneously at sunset, but the sun goes down fast,

at most an hour.

An hour.

An hour later, it's 15 degrees below the horizon.

You're done.

You're done.

You're done.

Okay.

But the farther away from the equator you go towards the poles, the sun's angle to the horizon gets shallower and shallower.

So

here comes the sunset.

And how long does it take to get deep below that?

Well, it's ambling its way along a hypotenuse,

along a slopey angle.

So twilight could last hours and hours.

Right.

Do you know all of England sits north of the northernmost part of Maine?

Wow.

I did not know that.

You know that.

Of course not.

Okay.

Yeah.

So.

Why would I ever know that?

So England has very long twilight.

Very long twilight.

Very long twilights.

Oh, is that why,

where is it?

Where they have like...

Oh, so if you keep going even farther north,

okay,

there is no night.

It's all twilight.

It's just twilight.

The sun never gets below your designated level.

If it's astronomical twilight, it stays above 18 degrees or above 12 for nautical, above six.

So then my wife is from Alaska.

They just

the midnight softball game on the solstice, the summer solstice.

Right.

Yeah, it's just twilight the whole time.

It's just twilight the whole time.

Yeah, so these are your twilights.

I don't know how many people know about them.

So recite them to me.

What are they?

So you got your civil, of course,

and then your nautical.

And then your astronomical, or as we're going to call that one, the Neolight.

Neolight.

No, it's got to be, no.

You don't like that?

No.

Because it's got your name in it.

No.

You don't want?

No.

No.

So there you have it.

Three twilights.

Nice.

And when we go observing on mountaintops,

we are given the time of astronomical twilight.

So we can plan our observing schedule around that.

Very cool.

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I'm Kais from Bangladesh and I support Star Talk on Patreon.

This is Star Talk with Neil DeGrasse Tyson.

Chuck, these don't stop.

Okay, that's fine with me.

Another explainer.

Excellent.

Okay, this one on clouds.

Have we done a clouds one before?

We've got better memory than I do.

We have not done clouds.

We have not done clouds.

Yeah, and you know, I wouldn't think there was a lot to talk about with clouds, and maybe that's why we haven't done it.

But have you looked at clouds from both sides now?

Okay, you mean top and bottom?

Joni Mitchell, forgive us.

So you ever wondered why clouds are just up there?

I mean, I know.

I mean, I haven't wondered.

I mean, once I found out that clouds were basically water droplets, just basically vapor.

Yeah.

They became extremely uninteresting to me at that point.

Okay, let me read, let me get you more, get your interest back going for a while.

Okay.

Okay.

All right.

Allow me to remind you that the sun does not heat the air.

That, I understand.

The sun heats the ground.

The ground, and the ground radiates.

And that heats the air.

And it radiates in what band of light?

Infrared.

Infrared.

Right.

And CO2 in the atmosphere actually traps infrared.

Right.

Oh, God, do I know that?

Okay, so.

What a shame.

So it's otherwise transparent to sunlight, to ordinary visible light.

But once the ground absorbs it, it re-radiates back infrared.

There, you get the trapping, what they call the greenhouse effect.

Okay, did you hear that, people?

That's how simple it is.

Did you see how simple that is?

Okay, comes in as visible light and passes through everything with no problem, heats the ground, ground sends it back

as infrared gets trapped, heats the earth,

climate change.

So, how do you know the atmosphere is transparent to visible light?

light?

How do we know?

Yes.

I don't.

No.

Because you can see the sun?

Okay.

No.

That makes sense.

If it were not transparent,

you wouldn't see the sun.

You can't see the sun.

You wouldn't be able to see the sun.

And there you have it.

Okay.

Right.

Let me be more blunt.

Windows are transparent to visible light.

Right.

How do you know this?

Because I can see through them.

You can see through them.

Right.

Walls are not transparent to visible light.

Because I'm not Superman.

That's simple.

Okay.

So Superman, back then, x-rays were like relatively new.

X-rays were discovered in like the first Nobel Prize in Physics was given for the discovery of X-rays.

Wow.

Yeah.

So it was the late 1890s, 1900 was the first time that was awarded.

So first Superman comic was maybe 1930s.

So x-rays are still kind of cool.

Yeah, they're like, woo.

All right.

But radio waves go through walls also.

Right.

So he could have had radio wave vision.

Then he'd have to tune in in his eyes.

Okay.

So, but back then, x-ray was just a metaphor for seeing.

Seeing through things.

Yeah.

That's all I wanted.

All right.

So infrared

does not pass through windows.

Not easily.

Not easily?

No.

Okay.

Do this experiment.

If you're in a fireplace, right, and you're at some distance from the signal, get someone to walk in front of you with a plate glass window.

In that instant, you don't feel any of the radiant heat from the fire.

The heat is

blocked.

It's blocked.

Right.

Okay.

Okay.

Okay.

That's cool.

It It blocks it.

So if you had infrared vision, a window is just the same thing as a wall to you.

Right.

Just think about that.

Okay.

All right.

So some things are not just inherently transparent.

They're only transparent to certain wavelengths of light.

All right.

So now.

And none of that has anything to do with clouds.

Okay, but that was still

framing information here.

Exactly.

All right.

Sunlight heats the ground.

The ground heats the air.

The farther away you are from the ground, the less heat you're getting.

That makes sense.

Okay.

Have you ever tracked the temperature in an airplane?

Sometimes they do it on the track thing.

Right.

Okay.

What's the temperature up there?

Cold.

Cold.

Thank you.

That's the temperature.

Is it exactly very, very cold?

It's exactly.

You measured it.

Exactly.

It's cold.

Okay.

It could be as low as 40 below.

Right.

Yeah.

40 below zero.

In Peggy Lee's fever.

Right.

All right.

And that's, we know, we all know that song.

You give them a few fever

in the morning.

Right, right, right.

So all the occasions where one gets fever.

Right.

Right.

One of the stanzas toward the end is, now you've listened to my story.

Here's the point that I have made.

Chicks are born to give you fever, be it Fahrenheit or centigrade.

Ooh.

Getting both temperature scales.

Yes.

In the song.

In the most sexist way possible.

And from a woman,

that's how bad it was back then.

That's how bad it was back then.

Even the women were sexist.

Chicks were born to give you fever.

No, here's why I even went there.

Go ahead.

Well, first of all, I'm giving him a hall pass because Fahrenheit is a human being's name.

Right.

Who actually invented the thermometer?

Right.

The mercury thermometer.

Also American.

Thermometer.

Centigrade, that's not somebody's name.

Right.

That's a scale.

So what they should have said was Fahrenheit or Celsius.

Right.

Well, then it wouldn't have rhymed.

Then it wouldn't have rhymed.

So that's why I got to give him a a hall pass on that one.

Okay.

Ask me why I even went there.

Why did you even go there?

Because the Fahrenheit and Celsius scale cross at 40 degrees below zero.

Oh,

interesting.

40 below zero.

You don't even have to say if you're not going to be able to have to say

the only temperature for which that is true.

40 below.

Yes, it is.

Yo, that's kind of...

That, right?

I'm ready to stop to explain it right now.

That is great information.

The only temperature temperature that exists both Fahrenheit and centigrade at the same point is 50%.

40 below zero.

And it's within a degree of the temperature that mercury freezes, which is especially relevant to mercury thermometers.

As you get higher, the temperature drops because you're getting farther away from Earth's surface with where the sun is heating.

This reverses in the thermosphere

where ultraviolet is absorbed by the ozone layer.

What does anything have to do with clouds?

Because clouds are formed in warm, moist, unstable air.

Okay.

If you're unstable, it means you're not going to stay where you are.

You're going to rise.

I have a pocket of air at sea level or just near the ground.

Oh, by the way, the official temperature that gets measured is at a predetermined height above the ground.

Okay, right.

Just so it can be standardized.

Yeah.

Otherwise, you'd have different temperatures.

A different temperature.

Everywhere.

You're up in a building, you get a different temperature there than if you're sleeping

on

a picnic blanket.

So they have to standardize that for this reason.

All right.

So now it's a pocket of air, and it has some humidity level in it.

Okay.

Okay.

Give me a percent.

Let's say it's 50% humid.

Okay.

Not bad.

New York City, that's very typical.

Yeah, enough.

Deserts, it's down in like single digits.

Rainforests, it's always up above 80, 90, 80, 90.

All right.

New York is 50%.

That humidity that is reported is actually a relative humidity.

Okay.

What that means is that is it is 50%

relative to how much it could carry at that temperature.

As the blob of air gets heated and rises,

the temperature drops.

Colder air can hold less humidity than warmer air.

Relative humidity goes up.

Gotcha.

It starts at 50 in this example.

It goes to 60, 60, then to 70, then to 80.

So let's take 80.

At 80%,

you didn't add more water to it.

No.

The capacity of the air to hold it dropped.

Right.

Okay.

So never mind.

So there it is.

It is ascending.

80, 90.

Bada bing.

You reach 100%.

Right.

100% humidity.

The humidity.

condenses out as water droplets.

Right.

Water vapor, basically.

Okay.

And boom, you have a cloud.

That's why the cloud is up there and not down here.

And now I know how clouds are born.

That's how clouds are born.

And all this time I thought you had a mommy cloud and a daddy cloud and they loved each other.

A stork cloud.

That's kind of dope.

And it's because of this temperature gradient from high temperature to low temperature from the ground on up.

Right.

Okay.

There are two ways you won't get clouds.

Okay.

No matter your height.

There's not enough humidity here

where even if it rises, it can go 10, 20, 30, 50, 70, and it never hits 100 before it gets way up in the atmosphere.

No cloud.

No cloud.

The other way is the blob of air has autonomy and a right to choose.

It doesn't have to have a baby cloud if it doesn't want to.

Is that where you were going with that?

Okay.

We were still on the baby making clouds.

Sorry.

Sorry.

Okay.

I had moved on from that, but I couldn't.

You couldn't.

I was still,

the juvenile brain stayed with me.

My childlike brain.

All right.

But that makes sense because it's really about the water that it's holding.

So

and the relative humidity has

capacity to hold.

To hold humidity.

Right.

Okay.

So now, so one way is it starts out so low, even though it gets high up, it never hits 100%.

Right.

No cloud gets formed.

Right.

Another way is if you have descending air.

Ooh.

That can happen.

So you can have, for example,

cold air moving through the mountains and cold air

is, and then it comes into a valley and it descends, it comes down over the mountaintops.

Okay.

If you have descending air, what's happening to the air?

The air temperature.

Well, it's getting warmer.

It's getting warmer.

So, and then condensation again.

It can now keep holding more and more moisture.

You're not making clouds.

Right.

So descending air does not make clouds because it keeps getting warmer.

warmer right ascending air with not enough moisture will not make a cloud because it'll never get to 100 right okay all right so far this is cool okay you ready okay so now suppose there's no wind and you got like let's say 70 humidity all right the sun sets and the temperature drops gets to 100

what happens what just happened we made a cloud where did where we where did we make the cloud where the air is i mean

thank you, Chuck, for that brilliant answer.

Right in front of me.

Yeah, of course.

It would be right here.

Right here.

Yeah.

We have a new word for that kind of cloud.

Do we really?

Yes.

What?

Fog.

You got me.

It's foggy.

That's fog.

And that's the cloud.

That's why when it's foggy, it's always a little cold.

Yes.

You ever noticed that?

Yeah.

Yeah.

It's a little cold.

A little chilly.

And it's a little dank.

A little chilly.

So the fog is when you get this, you reach, it's called a dew point, to be precise, the dew point, and it's right at the ground level.

Nice.

And so it's, it's interesting that in our language, you have a different word for a cloud above your head than for the same damn cloud right here, right in front of you.

If the cloud formation is vigorous, like the temperature dropped real fast, and it was really humid, and it, and it'll, it comes up there and it's still being unstable and it's rising and it's turning into

water droplets, You get a cumulus cloud.

Okay.

Okay.

If this is intense and it's unrelenting and it continues to build that cumulus cloud, which is just white with sunlight moving through it,

it becomes become less white.

Okay.

Because the droplets are getting bigger and bigger.

Oh, oh.

Okay.

And it starts getting gray.

Nice.

We have a gray cumulus cloud.

You get cumulonimbus.

Okay.

That stuff will hurt you.

So an accumulanimbus, now the water droplets are so, it is so laden with water, it cannot contain the humidity,

even at 100%.

And so the humidity nucleates, it finds droplets, dust in the air, things.

It says, and other

bits of water vapor collect to it.

And it's hell there for a while because you have updrafts because that's how you made the cloud in the first place.

Right.

But then it gets so big, it drops out.

Nice.

So the more vigorous the cloud is, the heavier the raindrops are.

Uh-huh.

Because it was holding them up.

Right.

Okay.

Right, right.

Very fast-moving air is holding it up until it can't hold it up anymore.

And that big fat-ass drop falls out of the sky and you get the big drop thunderstorms.

Nice.

Okay.

Now.

Let's say it's even more vigorous than that.

Uh-oh.

Okay.

We went from cumulus nimbus to cumulus negro.

That's when the clouds get black.

Yep, they get clouds.

They get black.

Okay.

So,

so the updrafts are so severe.

Right.

Okay.

Oh, I forgot to tell you.

Often the rain forms as snow,

as water crystals, right?

Because it's high up.

Right, right.

Okay.

Right.

Very cold.

And you can keep those pretty buoyant, but then as it begins to fall, it gets to a warmer air temperature and it just melts into rain right okay so all right now imagine updrafts so strong that not even the raindrops can fall out and it just stays up there the thing freezes and gets bigger and bigger and then one day i can't hold you anymore i gotta let you go and now it's too big to melt oh my god what do you get you got hail hail that's terrible you got hail

it's all because of the updrafts right that's updrafts that's an insurance cloud

So the conclusion here is the bigger the hail, that means the bigger the hail

pellets, spheres, the more severe the storm was.

Right.

Because it meant the updrafts were just so significant.

It was so catastrophic, turning just moist air into

giant balls of ice.

That's right.

Yeah.

By the way, with these puffy clouds, it's why they're more frequent in the tropics because you still have the ground heating, but you start out with such higher humidity air.

Right.

That when it rises, of course, you're going to puff up a cloud, like right there.

Now,

if you puff off a cloud here and not over there, then it could be raining over there and not over here.

Right, yeah.

Okay.

And this is the conditions,

almost all the conditions you need for a rainbow.

Okay.

Okay.

So to have a rainbow, you know, it's very specific.

I don't know if you knew this.

Okay.

Right.

So

it's got to be

raining in front of you.

It has to be

late enough in the day for the sun to be low enough in the sky for the sun to be behind you.

That makes sense.

Okay.

So it can create the...

There would be a late afternoon thunderstorm that's over there.

Right.

The sun is yonder.

And the sun is behind you.

Right.

Okay.

That's why you never see a rainbow in the middle of the day.

Because the sun sun is directly overhead.

Right, and it's not raining under your knees.

Right, right.

You would if in a sprinkler.

Right.

A lawn sprinkler.

But if you're in a plane looking down.

Yeah, yes.

If you're in a plane looking down,

you got to see it.

Yeah.

Awesome.

Yeah, you got it.

That's great.

Yeah.

So these are the configurations here.

And there are other kinds of clouds.

Like I said,

cirrus clouds that can be transparent, but they mess with our viewing of the night sky.

Little wispy things.

Wispy things.

Right, right.

And these are clouds that just hang out up there.

And

they're very stable, cirrus clouds.

And then you have weather fronts that come in, where there's a change in temperature.

You never heard of a warm front

coming in bringing bad weather.

Right.

That's not how that works.

It's always a cold front.

Because if things get warmer, you're going to hold more moisture.

More moisture.

It's when the cold front comes in.

Right.

The cold front comes in.

Messing up everything.

And you had warm air that had moisture.

Right.

And they meet at the boundary.

It turns your moisture into rain into storms into clouds right and so it's always the cold front you got to watch out for it's the drunk uncle at the cookout the cold front it's messing things up

all right so uh just one other interesting thing i think okay

and these are especially visible in airplanes you see these long i'll call them columns but they're horizontal columns of clouds yeah one after another yes these are called cloud streets cloud streets streets okay cloud streets okay because the clouds that i just described the air goes up but wait a minute if air is going up what's replacing that air gotta be more air

thank you chuck

that brilliant answer

okay so for every bit of air that goes up there's air that drops down and comes in to fill the gap so these are these are convective cells it's okay that's what's happening here but in a cloud street the convective cell is cylindrical.

Interesting.

Okay,

so imagine a horizontal cylinder that's rotating.

Oh, no.

Okay.

On the side that's rotating up, you get cloud formation.

And on the side that's rotating down, no clouds form.

Right.

Because it's going, it's downward air.

We've been through that.

Right.

Okay.

And so, but wait a minute, how about the other cylinder?

It has to be turning the opposite way.

Otherwise, they would cancel.

Right.

You can't have up air and down air simultaneously in the same place.

So these cloud streets have cylinders rolling with sides that match each other, both going down or both going up.

Oh, the next time you're in an airplane, look for this.

It's beautiful.

And it can go on for miles and miles.

Nice.

And these, so again, depending on how the terrain is heated, where the moisture is, is there a lake?

Is there an ocean?

Is there a

asphalt, which gets heats hotter than other reasons?

So, all of this makes for the beautiful diversity of clouds we see and love in the sky.

That's very cool.

And to think that all we ever do is look at them and see bunny rabbits and

deer and George Washington.

And always George Washington.

No, he's got the

president.

He's got the, you know, he's got the do for it.

That's true.

Yeah.

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So Chuck.

Yes.

Asking me about coastlines.

What's going on with coastlines?

I thought you'd never ask.

Well, we're in my office here, so nothing is ever farther than an arm's reach for whatever I got to use.

Okay.

So I'm just reaching right here.

And

look at that.

I got the whole word.

There you go.

In his hands.

Did anyone sing that anymore?

I bet they don't.

No.

No, because that was so kumbaya.

Yeah.

United Nations.

And it was like, bring it all together.

Bring it all together.

Hippie love, copy.

Hippie love.

Not anymore.

Days are gone.

All right.

Anyhow, so here's the earth.

When we think of earth,

we say to ourselves, there are bodies of water, oceans are the largest, and there's land.

And we see this and we think about it as though it's a fundamental feature of our planet.

That's Africa.

Right.

Because it has that shape.

Here's Asia with this coastline, and Japan is an island.

We have this understanding of the world brought to you by settlers and explorers and politicians Okay.

With a few wars thrown in here and there.

You always got to have a war, a good war to bring about changes

and geography.

It's also color-coded,

which I came to realize in my cynical adulthood,

are ways so that you can learn early on who your friends are and who your enemies are.

Because none of this is visible from space.

No, it isn't.

No, it's just land.

It's just land.

Okay.

Right.

All right.

So when you take a look at a coastline, there's the urge to think there's something fundamental about it,

but there isn't.

Oh, really?

That's just the coastline today.

That makes sense.

Okay.

Have you seen maps where you can look through the ocean, through the water?

Like, so in North America, for example, here we go.

Have you ever seen maps where you can see that the continent extends a little further out underwater?

Have you ever noticed that?

You know what they call it?

No.

The continental shelf.

Right, yeah.

You do.

I've seen that.

You've seen that.

Yes.

And so it kind of follows our contour, but it's way

out there.

Exactly.

And in fact, a lot of trash dumping activity in the old days, now you process the trash.

In the old days, they would put on a barge and go beyond the continental shelf.

Dump.

Dump it there so that it goes way down to the bottom.

Right.

Rather than possibly ever washing back up.

Okay.

And I remember looking at it as a kid and I said, why does the shape of our continent continue underwater?

I didn't understand that.

Ooh.

Because it's intriguing to me that that, okay, do you know what that other edge is underwater?

That's the coastline of North America when the ocean had less water in it.

Right.

When the oceans were drained.

Yeah.

Get used to that, people.

Get used to that.

Wait, hold on.

When the oceans were drained,

all these coastlines looked different.

Right.

They were bigger.

They were bigger.

They were bigger.

Yeah.

And so,

so, well, when were the oceans drained?

During the ice age.

Right.

You know how ice ages work?

You still have your oceans and you still have evaporation.

Because where does water come from that falls out of the sky?

It used to be in the ocean.

Oceans.

Ocean.

It didn't come from land.

No, of course not.

Okay.

It came from oceans and other bodies of water.

All right.

So the water evaporates up, but Earth is really, really, really cold.

So it goes into the cloud and then the cloud goes over land and it doesn't rain, it snows.

And deposits that water as snowflakes.

Okay.

So the snow is there.

Does the snow ever make it back to the ocean?

No.

There we go.

It stays there.

It stays there.

And then another snowfall comes and another layers on top.

And there's a feet and the yards and in some cases, miles.

By the way, this is a great opportunity to take the time and explain to people.

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It's real.

Okay, anyway, go ahead.

What happens is once the oceans evaporate out and it snows on land, by the way, it'll also snow in the ocean and then, okay, it'll just turn into water.

It's going to be water, all right?

So that's just fine.

But for every snowflake that lands, that goes to land and never melts,

you have systematically drained water from the oceans.

And if this goes on for thousands of years, you then build these layers of snow to make a new form of ice, which is glacial ice.

It's not snow and it's not ice in your freezer.

It's a different form of matter for the water molecule.

Glacial ice.

It's basically compactified snow.

All right.

It just stays there.

It stays there, frozen.

All right.

So you're draining the ocean.

And as you drain the ocean, oh my gosh, what happened?

Oh, back here

where Alaska and Asia meet with the Bering Strait.

Oh, our ancestors walked over.

Oh, they didn't take a boat.

What?

They didn't fly.

What you doing, Tuesday?

Let's take a walk.

Go for a walk.

So there they were in Asia, and there was a land and settlements there.

We've come to learn.

They crossed into North America after having risen up out of Africa,

risen up in terms of longitude, latitude here, up out of Africa into Europe.

Others went into Asia.

Some stayed low.

Others went high.

They get to that boundary.

They cross over and they settle North America, Central America, and South America.

Then the ice age ends.

Right.

Okay.

Oh, my God.

We're so trapped.

What happened to the Lamb Breaks?

Well, no, they've long forgotten.

Yeah.

Okay.

It happens kind of slow.

Right.

And then it covers over.

All right.

Many generations.

All right.

So what, yes, but you are correct.

With the water levels rising, changing all the coastlines, has now stranded a branch,

has now stranded a branch of the human species into North, Central, and South America.

So we strand a branch of the human species into North and South America and the water levels begin to rise.

But at that time

the coastline of the Americas was that continental shelf.

Right.

Now imagine if people started building cities on that continental shelf.

They'd all be gone today.

What a shame.

Okay, so what happens is the ice age ends, and the end of the ice age is a mixture of warmth and cold,

where the cold has retained glaciers for tens of thousands of years up here in Greenland.

Right.

And of course, down here

and

Antarctica.

And so

that period is relatively stable.

Yes, we have some storms and things, yes,

but

we have

sustained one of the most

climactically peaceful periods in recent earth history.

10,000 years of relatively stable climate,

post ice age.

And when you're relatively stable, you say, oh, well, where is the coastline?

Here is the coastline.

Let's put New York there or new amsterdam right why because it's on a river right you can have irrigation you have transportation you have um uh uh what else you use commerce commerce right okay business all right so the coastline of all the world's nations today

reflect

10 000 years of stable climate

the glaciers stayed glaciers in the cold parts right and other glaciers that had melted had filled up the oceans it's been stasis, relative stasis.

We are now warming Earth beyond that period of time.

Yep.

And so the glaciers that are still there, that were in kind of equilibrium with us as we built civilization.

And by the way, where are all major cities in the world?

They're on the water's edge.

On the coastline.

Practically, except for Denver, right?

Practically every major city in the world, famous historical city, is on some kind of waterline.

That's right.

Yep.

Okay.

So now we are warming the Earth.

The glacial ice on Greenland, let's find Greenland right there, and the glacial ice on Antarctica.

You say, oh, Greenland's not all that big and Antarctica's not.

Well, what are you worried about?

Big deal.

If we lose all the glacial ice in Greenland,

it'll melt and go into what?

The ocean.

The ocean.

We melt it on

Antarctica?

Ocean.

It goes into the ocean.

That's right.

Raising the sea level.

Rising sea level.

Okay.

If we lose all that glacial ice, the oceans will rise.

Now, the Statue of Liberty is actually on a huge pedestal.

Right.

I don't know if you knew that.

It's huge.

Yeah.

It is.

Almost as big as

it is.

At the bottom of the Statue of Liberty.

Yeah, no, that's what she sits on.

That's what raises up out of the bay.

Exactly.

Right.

So the water levels will rise so high that it'll reach her left elbow.

That's crazy.

That means there will be no more Manhattan.

Yeah, yeah.

You lose New York.

You lose New York.

You lose New York.

You lose lose all of North Jersey.

Not that anybody cares.

Said no one ever.

We lose New York.

And we lose North Jersey, too.

Said no one ever in the history of climate conversations.

We invited this guy,

the dude from Jersey.

But my mama lives in North Jersey.

So you lose all of that.

And it's a different coastline.

It is.

It's a coastline

without Florida.

There you go.

Oh, so there's one good thing to climb.

No, stop.

Stop.

Stop.

We got to protect all our 50 states.

So the average elevation of Florida is six feet.

Oh, forget it.

Say goodbye, Florida.

You know, Florida has the lowest, highest elevation of all 50 states.

Wow.

Right.

Can you follow that sense?

That makes sense because New Orleans is like below sea level.

So Florida has the lowest, highest elevation.

No, no, but in Louisiana, their highest elevation is way higher than the highest elevation of Florida.

Right.

That's what I'm saying.

No, you can have places with low elevation.

I'm talking about the average.

The average.

Okay.

Well, six feet would do it.

Six feet.

If you start with six feet, you ain't got nothing.

Exactly.

It's like, yeah.

So basically, your elevation is chuck plus an inch.

You're in a lot of trouble, man.

If you fly over, there's some satellite shots over Florida, and with the sun in the right angle, at the correct angle, you see these reflections off of these bodies of water throughout Florida.

Right.

So, of course, there's the Okeechobee Lake, which is the big one right there in the middle.

But you look around, it's like a body of water, body of water, body of water.

So it's like the water is already ready to take over.

It's like we're just, we're waiting.

One day we will all join with one another.

Abide your time, fellas.

Our time is at hand.

We have invited the oceans to join us.

Exactly.

The oceans are on board.

All we need now is time and their resolve not to do anything.

Their human stupidity.

So that's a whole other coastline.

Look at that.

So that's a whole other coastline of the future.

Look at that.

And so now you're going to look down on Earth and

there's nothing inherent about the existence of Florida on Earth's surface.

That's my point.

And there you go.

And there are other parts.

We'll lose a lot of in northern Canada, there's a lot of sort of low-lying lands.

Almost all of the South Pacific island nations are gone.

They also have very low elevations.

Get your vacations in now.

Get your vacation.

Florida, as we said, we lose Florida.

The Florida Keys, in fact, have even a lower elevation than Florida itself.

So they're gone.

And Can is gone.

We're going to lose Can.

Right.

I think he hung out at the Florida Keys.

Yeah, exactly.

So, anyhow, I just want to impress upon you that when we think of Earth,

there's nothing inherent about the existence of land poking up above the existence of water.

Right.

The water levels have changed over time, and they're changing now, and they're going to redraw the map once again.

Cool.

And not cool.

Like, it's a great novel thing to know and consider, but it's also terrifying that

we

the difference is that was a natural engineering of coastlines that you explained before.

That's a natural engineering of coastlines.

What we have now is

a

anthropomorphic engineering.

Right.

And in fact, like I said, we grew civilization on a stable climate and a stable coastline.

Right.

And

that took thousands of years before that to get to that point and stabilize out.

Right.

And now.

on a time scale of decades.

Decades.

Decades.

We're looking at maybe changing all of that.

All of that.

Yeah.

Yeah.

Whoa.

There you have it.

That is.

All right.

So, Chuck, I don't mean to bum you.

I'm just saying.

I'm so sad right now.

I'm so sad.

In fact, one last thing.

It's neither here nor there.

When we talk about how much water is on a body, the way geologists refer to it is how deep is the water if the water was the same depth everywhere on its surface?

It's just a way to think about how much water is there.

Right.

Right.

So if you take the water and spread it smoothly, like icing on a cake, and so no, it's not filling in the low parts or

trickling off the high parts, just have it go everywhere.

How much would it be?

So, you can say, well, how much water did Mars have?

If you give an answer, it'd be in those terms, it would have 50 feet of water, or a thousand feet of water, or 10 feet of water.

You'll just do this,

conduct this exercise.

When you do it, you learn things like Europa, one of Jupiter's moons, which is frozen on the outside and liquid underneath.

You add up that liquid, it's more liquid than all the oceans

on Earth.

Wow.

And since all our evidence tells us life began in the oceans, that's why we can't wait to get our hands on that ocean to see if there's any life forms

on Europa, which we would have to then call them Europeans.

Europeans, right?

Because we've lived on Europa.

What are you going to do?

Or we could just call them, you know, space white people.

What?

They're Europeans.

Oh, if they're Europeans.

Don't.

They're jokes.

They're jokes, people.

Stop it.

So that's it.

Chuck, that's yet another Star Talk Explainer delivered to you from the Cosmic Crew.

Aha.

Yeah, at the American Museum of Natural History, Hayden Planetarium.

Neil deGrasse Tyson here, as always.

Keep looking up.

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