Snow day!

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All right.

It is the day after a very intense snow storm here in New York City.

And my editor, Joanna, came for the idea

that I should go inside and talk to people about the snow.

So I am looking out at what can only be described

as a winter wonderland.

Everything is truly covered.

It's like not a blanket.

It's covered in a quilt of snow.

It's like fluffy and white and charming and cold.

I don't want to go outside.

Oh, it's so windy.

Do you hear that?

All right, let's go.

A few weeks ago, I had an extremely nice time,

wander around the streets of Brooklyn and Prospect Park

and talking to people about the snow.

I can say this park, it's beautiful.

It has a lot of trees and all of the trees are really snowy.

I can see a lot of snowmands.

There's a huge snowman over there.

Like, I don't know how to say it in feet,

but I can say it's at least 160 centimeters.

We realized this morning that this was the best snowman

making snow that I've ever seen.

And so we made this snowman this morning.

Now we're back to give it a personality.

So how about something else?

Help.

Help what?

You're about to slip.

Well, we already built a snowman.

And we've all left in the park.

So now we're going to go get some hot cocoa.

I talked to people who were shoveling their rock waves,

going sledding, going skiing.

I am wearing my cross-country skis from high school.

How are you fitting cross-country skis

in your New York apartment?

That's a great question.

I talked to people with lots of thoughts on snow.

I love working out.

I love shoveling it.

I cross-country ski.

I just love it.

Prosnow, love it.

Except a month from now, when we still have it.

And it's black.

Like, once it gets disgusting like the last snow did,

then I'm over it.

But I like this snow for right now.

I love it.

From a distance.

Only because these small we out here

I've let it net out a bit in my house.

But I do love it from a distance now.

And I also ask people if they had questions about snow.

Well, I know that it makes things very quiet

because it absorbs sound.

But I don't understand.

I guess I don't know the science behind why.

I did it here.

I'm not sure if it's true that every snowflake is different.

I guess one question would be, sometimes when snow falls,

you can't really make snowballs out of it.

And then sometimes it's perfect like this

where you can grab it and make a snowball.

Yeah, just what determines that?

Because this feels like a totally different ballgame.

So not everyone had questions for me.

Not really.

I kind of like not knowing how things, yeah, you know what I mean?

OK, great, I'll go home.

That's not what I mean.

That's not what I mean.

I did get enough questions that I decided

to call up a snow scientist in search of some answers.

So I am Bird Pinkerton.

And today on the show, I'm talking to Jessica Lundquist.

She's a professor of civil and environmental engineering.

And she's going to answer a whole bunch of questions

about snow for us.

Of course.

This is unexplainable, though.

So a little later in the show, she's

also going to tell us some things about snow

that she does not yet know and is still trying to figure out.

All right, well, I have a bunch of questions for you

as our resident snow expert.

Let's go.

So the first question I got from a few people

is actually about the shape of snowflakes.

How was it formed?

How does design come about?

Like, does there anything that makes it

have a different shape, the snowflake?

Why are snowflakes all different shapes?

So snowflakes will form around a tiny speck of dust

called a condensation nuclei.

OK.

But now it can grow in different ways.

So you can grow out to make what we call a dendrite shape.

So that's your postcard snowflake.

But it could also grow down, right?

So you can also get a column, which one of these you get

will depend actually on the temperature

and water vapor content in the atmosphere

where the snowflake is being formed.

Depending on the conditions in the atmosphere,

it will grow in a certain way.

And then it's not sitting at just one point in the atmosphere.

It's often like being blown up and down

to different points with different amounts of water vapor,

different temperatures.

And so it's often like growing differently

throughout its lifetime.

And then as to fall from that cloud down

to where we are at the surface.

And it will often like hit different snowflakes.

And then they can aggregate and you can get

these sort of messy, big things.

Wait.

So what you're saying to me is like, the snowflake's shape

is like a record of the life it's lived almost like where it's been.

Yes.

So it's telling you about where it's been in the cloud

and what it's fallen through and whether it hit another snowflake

and how it grew.

And if you really want to know about snowflakes,

I recommend checking out Ken Lieberk to grow

some of his lab at Caltech.

He can make designer snowflakes.

Every day I learn about a job that I wish I had.

OK.

So the answer to this first question of sort of like,

why is every snowflake different is like every snowflake has

its own little individual path through the atmosphere

that shapes how it grows.

And then also go check out this guy's designer snowflake lab.

Yes.

Question two is I got a question kind of about not how it looks

but how it sounds.

So one of the people I met did sort of like an ASMR demonstration

of the snow crunching.

And then was asking, why does it crunch like that?

So you talked about the snowflakes history in the atmosphere,

but then the snow also falls on the ground

and has a history on the ground.

So your snowflakes started accumulating on the ground

and you have all these little individual snowflakes

that fall on top of each other.

And they have air in between them.

It's not ice.

It's a pile of little snow crystals with air in between it.

Like a fluffy pillow on those.

The way that your pillow is like a bunch of feathers.

Except this is cooler than feathers

because snow is always close to its melting point.

So if you think about some arterial science,

if you have like metal and you heat it up

so you can weld it and center it,

if you get your metal really close to its melting point,

you can like make two points of metal

actually attached to each other.

So snowflakes will do something we call centering.

So you also center things with metal.

But snow will center by itself just sitting there.

So your snowflakes fell down.

They made kind of like your feather pillow with air inside.

And then your little crystals start attaching themselves

to each other.

So now you have this matrix of snowflakes

that are attached to each other.

And then underneath it they have air.

You could also have right at the surface

it might melt and re-freeze a little bit.

So they'll often be you know,

attached at surface with air underneath.

Now your crunchy style, you're breaking that.

Oh, you're breaking the connections that they formed.

Yeah.

But it's only sometimes your snow won't always

make a crunchy noise, okay?

So basically like because snow is slightly melted almost,

but it has the power to stick together.

It's forming all these sort of fragile bridges.

Yes.

You crunch it.

You're just demolishing a lot of bridges.

All at the same time.

Great.

Another sound question.

This is question three.

Why does snow absorb sound?

Okay, and this it doesn't always do that either.

So one thing is snowflakes are all different.

The snow on the ground is also all different.

So sometimes it might make a crunchy sound

and sometimes it might absorb sound.

So when it most absorb sound is right after new snowfall.

So it hasn't yet had time to make all these

sintering connections.

You just have a whole bunch of little snowflakes

just loosely lying at surface.

So think of kind of like your feather pillow,

not yet attached, but lots of air in between it.

So the sound gets kind of muffled by going into all those

air pockets in the snow and doesn't get reflected back

to your ear.

So it ends up sort of being a sound absorber

because it's just loosely connected

a whole bunch of air pockets.

Delightful.

Okay.

So then I got a lot of questions about why the snow is

the way that it is.

So people were talking about sort of like the texture

of the snow in this storm versus the one two weeks ago.

It seems like thicker and stickier.

And like the fluffiness, what makes it so fluffy?

One person got really descriptive.

It's like AI snow.

What do you mean?

Like I feel like it was 3D printed.

Yeah.

It's like tempered pedic snow.

But it's apparently like better for snowballs,

better for snow building.

Yes.

And people wanted to know like what was going on there

essentially like physically, chemically, whatever

to make different snows after different storms.

Yes.

So again, we talked about the history, right?

It starts with they're falling through the atmosphere.

They fell through different atmospheres, warmer storms,

cooler storms, depending on the conditions in the atmosphere.

Snow crystals grow differently.

And they also have different amounts of liquid water

inside of them.

So if you get a colder storm, you have a lot less liquid water.

And you end up with you dry snow.

It won't make a snowball, right?

So as you get warmer and you get the biggest change

above negative three degrees C.

So as you get between, again, when we talked about snow

being really close to its melting point, right?

So snow is melting points about zero degrees C.

And as you get really close to that,

you actually get more molecules that actually are liquid.

And that makes it really sticky.

You can build good snowballs with warmer snow.

One person asked how it accumulates on surfaces.

And so specifically, we were talking about tree branches.

And then I was thinking about wires.

And I was curious if there's any interesting physics

or whatever going on structurally there.

So there are actually these amazing studies

done both in Japan and in Switzerland,

where they put out all these boards of different widths

and different sizes.

And then they just measured how much snow accumulated

on all of them.

The pictures and their papers are really cool.

Yeah.

And they also did studies where they tried

to see like how tall could you stack snow

and like what was angle of repose of just the stack of snow?

So these are questions that lots of people have.

Maybe not lots of people, but it definitely

been studied quite a bit.

It gave us back to some of the things

we talked about before.

So how much snow you can stack up actually depends

on the temperature of the snow.

So again, we got back to that snow

being really close to its melting point,

particularly if you have a warmer snow storm, right?

And the fact that the snowflakes can

center and stick to each other.

So they will actually attach themselves to each other.

Also, the stickiness per se of snow

goes up hugely between negative three degrees C and zero degrees

C. And if you think about like little bits of it

will like melt to be liquid and then re-freeze again,

that it will sort of freeze itself

on to your tree branches and your different things.

And then it will like touch itself by centering to each other.

And so it's and stack up amazingly.

Wow.

OK.

I'm learning a lot.

Unrelated to structure of things.

One person asked what the benefits of snow

are for the environment.

So like for trees or for parks, et cetera.

Snow insulates things really well.

Just like in your house, the insulation

is a lot of pockets of air in between two walls, right?

Your snow builds up with a lot of trapped pockets of air

that insulate the temperature.

So it turns out that in most cold regions,

the temperature at the top of the snow pack

above the snow is significantly colder

than the temperature at the base of the snow.

So if you go to the Arctic, it's often

like more than 20 degrees Celsius different

between the top and the bottom of the snow.

So it'll be, you know, like can get negative 40 in the air.

And if you're under the snow, you're super warm.

So if you're out in a really cold storm,

you could dig yourself a snow fort, bury yourself under the snow,

you'll be warmer, right?

So a lot of animals live under the snow,

some hibernate under the snow, some many build their dens

under the snow, right?

It's a warm safe place through the winter.

And is it, is it just animals?

Are there other things kind of taking advantage

of this warm blanket effect?

Plants, microbes, you know, things in the soil

that are using that same installation to survive,

like plants with shallow roots in cold regions,

often have root damage if there's not a good snow year.

It's kind of counterintuitive that often in years

with less snow, it's colder for a lot of plants and animals

because they can't hide under that blanket.

So clearly there is a lot about snow

that's no mystery to Jessica.

But there are some things Jessica does not know about snow.

So after the break, it's snow mysteries with Jessica.

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All schools are officially closed for a snow day.

All right, Jessica Lundquist was patiently answering

all our questions about snow.

But I also had some questions about Jessica,

like what got her into studying snow to begin with?

She told me she grew up in California

and her favorite thing to do was to go to Yosemite.

I just like going in the mountains and going hiking

and they went in the summer, which, you know,

generally there's no snow.

But then quickly realized that the amount of water

in the river that I like to jump in and go swimming

was completely related to the amount of snow

in the mountains.

So you were like, I'm going to spend a great deal

of my career studying this question.

And no, of course not.

I said, I want to be a park ranger

and just go hiking in the mountains.

She did wind up becoming a researcher though,

not a park ranger.

And she began tackling this big question related to snow.

How much snow is there actually in the mountains?

It turns out that on the west coast of the US,

snow melt can be an important source of water.

So basically in the Western US, we

don't have enough water for all the things

we want to use water for.

There's a lot of people living in the West.

There's a lot of crops grown in the West.

All of these need water to grow.

And basically, the water is allocated to people

through this water right system.

So in terms of what is the value of snow,

it's like free reservoirs.

It's storing that water in the winter for the summer.

So people always want to know how much water exactly

do we have in the snowpack?

Because it's actually so dry out here

that people will be told, don't plant.

We can't give you water this year.

You can't plant your crops.

You need to furlough your fields.

You need to do something else.

So a lot of what I try to do is figure out

how much snow there is in the mountains at any given point

time.

And the job is often to predict the future.

I think, can you predict how much water

will have in the future?

But this is easier said than done.

Because it's tricky to measure how much snow there is

in the mountains.

A lot of snow falls in places that don't have roads,

that don't have infrastructure.

There are rugged, steep terrain without a lot of access.

So a lot of it fell in place.

You can't go.

But it's extremely variable.

So if you put out a measurement site,

so the National Resource Conservation Service or NRCS

has something that's called a snow pillow.

So it's basically you have two metal plates.

You fill it with antifreeze.

You put it right on the surface of the ground

and you bury it slightly so bears can't find it.

The snow falls on it, squeezes the water in the antifreeze,

which then creates a pressure gradient.

And it tells you how much, what is the weight of the snow

resting on the snow pillow?

So basically that weight tells you what we call

the snow water equivalent.

For basically, for water resources,

if all that snow melts, how much water do we get out of it?

This is the snow water equivalent.

Or you may heard the term sweet.

That's the WEs, the water equivalent.

I have not heard the term sweet, but I like the term sweet

quite a bit.

OK.

That sounds great.

That sounds like we have a measurement.

Fantastic.

Exactly.

But if you walk 10 steps to the left,

you're going to measure something completely different.

Oh, right.

OK.

So it's somewhat less sweet.

The same problem exists for other measurements.

And satellite images can be tricky.

And so Jessica and researchers like her

may never be able to work out a perfect measurement

of the snow in the mountains on an eager year.

What they can work out, though, is patterns.

So for many decades now, people

have been taking measurements of snow

in the mountains at certain spots.

And then seeing how much water there

ends up being in the following warm season.

And that means that they can say, you know,

when our measurements look like this

in these various spots, there will probably

be this amount of water.

Emphasis on probably, though.

Because the predictions are not always as neat and tidy

as this makes it sound.

So that's why I'm still employed.

So the number of things can trip people up.

One thing we did recently, so basically Colorado.

Colorado River provides water for what, seven different states

who all argue about much water they get.

And as often in the news, it's not having enough water.

And what they've noticed is since 2000,

the amount of water in the river was less

than what snow predicted.

And 2021 was a particularly bad year.

They thought from the snow pack, it was kind of close to average.

And then it delivered way less stream flow than they thought.

And so, you know, then people aren't prepared

because they bought their seeds to plant.

And then they get the water cut off, and they lose their crops.

And so it's for some people economic disaster

to get this forecast wrong.

Jessica says, the reason these forecasts were wrong

was that it had stopped raining as much in the spring

in Colorado.

And so if it is super dry and warm in the spring after April,

after they take that survey, it turns out

that the plants wake up early.

And it's sunny.

And they say, OK, I'm going to start using water to grow as a plant.

They start transpiring, evaporating.

And a lot of that water goes back to the atmosphere

instead of in the stream.

So the plants before it can even get to the stream,

the plants near the snow are like vacuuming it up

in a variety of ways.

Yeah.

Is climate change affecting your predictions at all?

So basically, climate change, warmer temperatures,

the biggest impact is that more precipitation falls

as rain instead of snow.

So now, in terms of predictability, rain is fast, right?

When it rains, it runs off right away.

So the snow pack, what it does is it actually allows us

at this time of year and at traditional April

for snow surveys to say, this is how much water is

going to be in the rivers in the summer.

We actually have no idea how much it's

going to rain in May or June in the Western US right now.

That we can't forecast, right?

And without the snow, it's that kind of guess

of how much will it rain in the future that we have to rely on.

So snow itself, by virtue of just storing the water

on the hillside, gives you a lot of predictability

that we don't have when it falls as rain instead of snow.

Fast-needing.

All right, easy question to end.

Is there a snow that you would revisit from your life

that you'd encountered?

Yes.

So I did a project.

We were staying snow out in Gothic Colorado,

which sort of I crushed it, but you'd

middle and lower Colorado Rockies.

We were staying in this old abandoned mining town

that is now a biological research station

that you can only access by skiing in.

So we've skied in and we're staying in this old mining town.

And every day we are cross-country skiing

out to our measurement sites to dig in the snow and measure things.

And so we're the only people out there.

And it's like snowing really lightly.

And I was a front of the line of everybody

heading out just sort of cross-go-through skiing on our route.

And then all of a sudden, right in front of me,

I've disturbed a bunch of tarmigan that

were hiding under the snow.

So the tarmigan, especially when it's really light, fluffy snow,

they will like bury themselves in the snow.

But as I went by them, I scared them.

So all of a sudden, the snow erupted

and a whole flock of white birds flew out of the snow

right in front of me and all around me.

It was like the snow erupted birds.

I mean, it was beautiful.

That's so magic.

I keep looking online.

Like, has that someone videotaped this?

I can't find a YouTube recording of like

tarmigan erupting from snow.

If you ever find one, you have to send me.

OK, this is perfect.

We brought, we came to you with questions that people had.

And now you are leaving our audience

with a question that you have, which is, does anyone

have videos of tarmigan erupting from the snow?

Well, I'll let you know if anyone sends us any.

Thank you.

If you want to read more about Jessica Lundquist's research,

you can find her at the University of Washington's

Department of Civil and Environmental Engineering.

This episode was produced by me, Bird Pinkerton.

It was edited by Joanna Salatarov.

It was also her idea to send me walking

through the cold and snow.

It was one lovely person I spoke to, put it.

I'm going to come out and do some of this.

I'll let her know.

Christian Ayala did the mixing and the sound design.

No, I'm Hassan Feld, does our music.

And Melissa Hirsch checks our facts, Jorge Just, Meredith

Hadnott, Julia Lungoria, Sally Helm, and Amy Padula

are the fact that some macaques in Japan

have been recorded making balls of snow

that they roll down hills.

Thanks so much to everyone who gave me their questions

and their thoughts on snow.

I really appreciate you all.

And if you have videos of tarmigan bursting from snow,

please send them to unexplainableadvox.com.

If you have videos of any birds bursting from snow, honestly,

or animals bursting from snow, send those along

to unexplainableadvox.com to these.

Also, I had a ton of fun producing this episode,

like sort of an irrational amount.

And I was thinking I might do another episode about snakes.

So if you have snake-related questions,

please record a voice memo and send it to us.

No question is too silly.

Just tell us your name, your age, your question about snakes.

And we might use it on the show.

We are, in case you missed it, unexplainableadvox.com.

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