- [Maiya May] Inside of a thunderstorm like this one
updrafts of nearly a hundred miles per hour
can lead to a tornado or something much weirder
that costs billions more in damages each year.
(hail falling)
Hail.
Frozen, sometimes giant chunks of ice,
falling from the sky on a warm summer day.
- [Woman] Oh my God, that was huge.
- [Man] This is the kind of hail
that will come through a roof.
- While it may not seem as scary
as many other natural hazards,
it causes over $10 billion in damage each year
across the U.S.
Today we're going to visit a lab whose top scientists
fly across the country on a moment's notice
to find and 3D print record-breaking hailstones.
They also use an incredibly complex potato gun
to make holes in roofs.
Their goal is to figure out how to decrease the damage
hail causes and how Hail stones get so big.
- [Man] Look at the size of this piece of hail.
(hail crashing)
- [Ian] Hey Maya, welcome.
- So, we are at your hail lab.
- We are, so we are going to go make some lab hail,
and then we're going to go shoot it at some shingles.
- [Maiya} But first I wanted to know just how big hailstones
can get and how they grow so large.
- So this is the United States and current world record
hailstone that was found in Vivian, South Dakota.
This one is the recent record for the state of Texas.
These are 3D prints and it comes in over five inches
in diameter and you can see it's really flat.
It's very oblique, that one's a little more round.
- Yeah, I would think, I don't know.
I'm sure some people think of hailstones
as like perfect circles.
- Yeah, that's right.
So, so hailstones.
- These are not.
- That's right, they get less spherical
as they get bigger and they start to get all these spikes
and knobs and all these kind of crazy shapes.
And that actually plays a role in how fast they fall
and how much energy they have when they hit things.
- [Maiya] And they do hit things.
Ian told me that hail forums when a thunderstorms updraft
stretches clouds high enough into the atmosphere
that the air temperature dips so low,
that water droplets turn into ice.
And if updrafts hold them there long enough,
the water droplets and ice freeze together
making hail larger and layered.
When a hailstone gets too heavy or the updrafts weaken,
it falls thousands of feet to the ground.
- And it took a column of rising air
that's over a hundred miles an hour.
So think about air going up at a hundred plus miles an hour
to keep that stone and this one,
a loft to be able to grow to these gargantuan sizes.
- And how fast are these coming out of the sky?
- So this one, on record, is gonna be falling
at over a hundred miles an hour.
This kind of hailstone will actually fracture
the plywood deck and perhaps even go through a roof.
- [Maiya] In fact, hail causes so much damage
that there have been efforts over centuries to stop it.
300 years ago, Europeans tried firing cannons
into clouds and ringing church bells.
In the U.S., Russia and even Canada cloud seeding
by dropping silver iodide via plane or rocket
was and still is attempted to decrease damage.
But still, giant hail up to the width of a volleyball
falls from the sky.
So the folks at IBHS decided to work on changing
the way we build rather than changing the weather.
That included creating a machine
to make accurate size and density hail.
How accurate is the recreation of these hailstones?
- So it's actually pretty precise.
We've gone to the field and basically done scientific storm
chasing to go make all sorts of measurements
of real hailstones.
So we know what the distribution of how strong they are
and what their density is.
And we can actually vary the density of the ice,
how strong it is.
So how much force it takes to fracture it.
And we can dial up those knobs to basically replicate
what we see actually out from thunderstorms
in the real world.
- [Maiya] That's where the hail collection comes in.
By 3D scanning hailstones in the field,
3D printing them the size and weight and flying them
in a skydiving chamber, Ian and his team learned
that the unusual shapes of hailstones
actually act like helicopter rotors.
When they grow this large, the flattened shape
and protruding knobs make the stone spin,
allowing them to stay aloft in a storm for up to 30 minutes,
growing larger and larger.
But the two inch diameter size hail
that they create in the lab would take just a few minutes
to form in the atmosphere.
- We've made our hailstones, so we're gonna now
take them over here and we're going to go put our shingle
panel to the test.
So Terrence, over here, is going to take each hailstone,
he's going to do his measurements and weigh the stone
and, if it's in our specification, we're good to go.
He's going to walk over and load it up into our barrel.
- [Maiya] Okay.
- And then for this case, where we're aiming
somewhere in the range of 68 to 75 miles per hour.
- [Maiya] But they're not just shooting new roofs.
The lab has actually been weathering them for 20 years
in a roof farm before putting them to the test.
(barrel shooting)
- Wait, what happened with that one?
- It was our hard bounce.
So that's where the stone was so strong
it just bounced right off the shingle.
- Okay.
- And so that's one of the impact modes
we're actually targeting.
So a hailstone, when it hits a shingle,
can do basically three things
and it's all determined by strength.
It could one, turn to slush,
basically shatter into a whole bunch of pieces
and leave that kind of snow cone, little pile of ice there.
That's a soft hailstone.
They can shatter into a bunch of different pieces,
but not leave that residue.
That's a harder stone that just shatters.
And like we just saw right there, they can bounce off.
And those are the really strong hailstones
that can take several hundred or even a thousand PSI
to actually fracture those things.
- [Maiya] And that's what puts holes in your roof,
siding and windows.
If a roof is mostly undamaged,
it means their work is paying off.
Even after decades of aging, it's still doing its job,
often because of one revolutionary ingredient.
- So some of the good performing products
that we've started to see coming into the industry,
all have something in common.
They're actually made with a polymer additive,
and this is a stick of polymer material.
So we're going to go ahead and pull it
and I'll show you why this matters.
So Maiya and I are going to pull this stick a polymer
and notice how it stretches.
We can stretch, stretch, stretch, stretch.
I'm not going to let go because one of us will go fly.
- Oh my gosh.
- [Ian] But there we go, look how far we can stretch this.
- Wow.
- And if we let it go, it'll actually kind of reform
to the shape it had.
So let this sit for a minute or two.
But this is added, now, into a lot
of the good performing shingles we see.
That helps give just enough flexibility
to be able to handle those impacts a lot better.
- [Maiya] What IBHS has not figured out
is how to create a hail resistant car.
An intense hailstorm can destroy a vehicle,
breaking windshields and denting the body.
Ian's research on how hail forums
will eventually help forecast which storms
create large and destructive hail and which won't.
But until then, here's his advice
if you get caught driving in one.
- Find a good spot to duck under covered parking,
a gas station awning, a bank.
The one thing to avoid doing is stopping under overpasses,
especially on interstates.
That can cause huge traffic jams.
If you're caught and you have nowhere to go,
just keep driving if you can and you will get out of it.
Swaths of hail have really tight grading.
So you can go from big hail to basically rain
over the course of half a mile.
So keep driving, keep moving.
Don't necessarily sit there
cause you can find yourself in a slow moving storm
just getting pummeled.
(hail hitting)
- [Man] Look at those hailstones.
- [Maiya] Have you ever been caught in a hailstorm?
Tell us your story in the comments below.
(calming music fading)