Original subtitles

Narrator: worldwide, 6 billion Cameras are watching us.

On our streets, at work, And in our homes,

They capture things That seem impossible.

It defies the laws of physics.

Kays: aw, This is unbelievable, man.

Narrator: experts carry out Forensic analysis

Of these unusual events.

There's got to be some Explanation for what's going on.

[ screaming ]

[ horn honking ]

Narrator: coming up -- Highway hellfire.

Spontaneous combustion On the freeway.

It's a giant fireball.

It looks like a special effect, But this is terrifyingly real.

Narrator: beast from the abyss.

A drill team encounters An underwater alien

In the ocean depths.

Kays: this creature doesn't look Like anything else

I've ever seen -- More like an alien

Than any creature From a textbook.

Narrator: And a killer fog spreads Through an illinois town.

Pojman: if you get caught In this cloud,

Your chances of survival Are next to zero.

Narrator: bizarre phenomena.

Mysteries caught on camera.

What's the truth behind This "Strange evidence"?

♪♪

-- captions by vitac -- Www.Vitac.Com

captions paid for by Discovery communications

A traffic camera in china, and A truck spontaneously explodes.

Just an enormous explosion.

It's a completely Heart-stopping moment.

Narrator: investigators sift The wreckage for clues

About what caused This freeway fireball.

We've all seen collisions, but Never an explosion like this.

♪♪

Narrator: hangzhou, one of China's most congested cities.

There's 7 million people And 2.5 million cars.

July 17, 2017.

Road cameras are keeping tabs On a normal rush hour

When one captures A bizarre event.

♪♪

This is straight out of A summer action movie.

we see a truck, coming not At a super high rate of speed,

collide with a truck that seems To be parked on a highway.

And then a spectacular Explosion happens.

♪♪

Narrator: road accidents Are widespread in china,

Killing over 250,000 People a year.

But normal collisions don't Result in a massive firestorm.

The scale of the blast Baffles experts.

It looks like a special effect, But this is terrifyingly real.

Bartolo: amazingly, nobody was Hurt in this explosion,

but you could easily imagine A different outcome.

Narrator: professor of chemistry Andrea sella

Examines the footage.

He speculates that The mystery explosion

May have been caused By a deadly chemical cargo.

for me, the principal question That's in my mind is,

"What's onboard that vehicle?"

The obvious thing that springs To mind is nitroglycerin,

The great explosive that Is at the heart of dynamite.

♪♪

Narrator: nitroglycerin is made Up of unstable molecules.

They burn quickly, Creating intense heat

And rapidly expanding gas.

The result is devastating.

It's a contact explosive.

A physical shock is enough To set it off.

China uses vast quantities Of this explosive

To extract metals and minerals.

All of our mining industry Is really driven by explosives,

Because that's how you Break the rocks apart.

♪♪

Narrator: Pyrotechnics specialist Mike sansom wants to see

If nitroglycerin's Explosive properties

Match the fireball Caught on camera.

so, this here is nitroglycerin.

It's a primary high explosive.

It's impact- And friction-sensitive,

And when it detonates, it goes At about 7,000 meters a second.

Let's give it a go.

Narrator: with a substance as Powerful as nitroglycerin,

Sansom delivers the tiniest Of droplets to the test pad --

Just 1/480 of a fluid ounce.

Sansom: I'm gonna hit it With a hammer to see

If this impact Can set it off.

Oh!

♪♪

I mean, the force of that Went straight through me.

It just blew up.

I mean, it blew it To smithereens.

Narrator: but sansom detects A key difference

Between this explosion and the Mystery blast in the footage.

Sansom: it's almost like the Video, but not quite.

There were no flames, And there's no smoke.

So what was it?

It's got to be something else.

♪♪

Narrator: material scientist Kishore hari spots a clue

In the footage -- Debris coming out of the truck.

Hari: what seems to be Coming out are bits of paper.

And that's really Unusual because,

Even though paper is flammable,

We don't think Of paper as explodent.

Narrator: when image analyst Conor mccourt examines

Footage of the aftermath,

He identifies an intriguing clue

In the cargo of The fire-ravaged truck.

If we look at the video footage,

We see containers On the back of the truck --

Very suspicious.

Smoking containers here.

Paint container, all charred.

What I suspect is that there's Another material back there,

Which would make sense to be In the back of a truck

That's carrying paint, And that would be paint thinner.

Narrator: strangely, Neither paint nor paint thinner

Are combustible,

But there's a byproduct Of them that can be.

♪♪

With paint or other materials That involve volatile compounds,

They release gas From the liquid.

And that vapor can be Flammable a lot of times.

It's not so different From holding a tank of gasoline.

It's not the gasoline itself That's combustible.

It's the gasoline vapor.

If you have something flammable In the back of your truck,

Some kind of flammable liquid,

If it's very hot back there, It can start to off-gas.

Sella: you can imagine that On a hot, sunny day,

If the solvent Began to leak out,

You could quickly reach A really saturated atmosphere

Inside the back -- An explosive mixture.

And then, it's -- boom.

Narrator: frame-by-frame Analysis of the video

Confirms flammable fumes

Bursting from the back Of the truck.

Mccourt: there's a point Of contact and puff.

We see white smoke come out.

Then, boom!

We see a huge explosion.

That puff of smoke is a clue

That there's some gas

Trapped in that one van.

And I think that's Our fuel source here

That catches on fire.

Narrator: so, what could have Caused these fumes to explode?

♪♪

Coming up -- a terrifying, Toxic fog smothers a town.

People are running away From something.

They're clearly fleeing For their lives.

Narrator: deep-sea drillers Find a monstrous

New life-form in the abyss.

This creature doesn't look like Anything else I've ever seen --

More like an alien than Any creature from a textbook.

Narrator: and what's the trigger That turns this truck

Into a freeway fireball?

It's a completely Heart-stopping moment.

This truck was a bomb.

♪♪

Narrator: experts investigating A highway horror

Blast discover that flammable Fumes from paint solvents

Build up in the confined Cargo hold of the truck.

But they have no idea What ignites

This deadly chemical cocktail.

This is a one-in-a-million Happening on a highway.

Narrator: chemist andrea sella Suspects

That metal-on-metal impact

May have sparked the explosion.

Sella: that vapor was just Waiting for a spark,

which was provided

by the collision With the other vehicle.

The result is going to be A big, orange fireball.

Narrator: explosives expert Mike sansom re-creates

The conditions In the back of the truck.

He wants to see if a gas Byproduct of paint thinner

Could've created a fireball Of the ferocity

Seen on the surveillance video.

it's just a tiny, little bit Of a liquid solvent.

I'm gonna put it in this to Represent the back of my truck.

Narrator: the solvent off-gases Into the container,

Combining with the oxygen inside

To create potentially Volatile fumes.

Sansom: let's see what happens When I spark it.

Whoa!

[ laughs ]

I mean, it blew The lid clean off.

♪♪

The crucial thing here Is that it was

The perfect mixture of air

And solvent that made This explosive environment.

A single spark, And it blew it apart.

♪♪

So, in a sense, it is a bomb.

It is an inadvertent bomb, But this truck was a bomb.

Narrator: A perfect storm of events

Triggers this Nightmare scenario.

Worldwide, millions of gallons Of paint thinner is produced

And transported each year.

It would seem that No street or town

Can escape the threat of Just such a freak fireball.

♪♪

Now, a nightmarish creature Emerges from the deep.

It looks like something out of "Independence day"

Or a facehugger from "Alien."

What is it?

Narrator: experts have no idea What it is or what it wants.

Doesn't make any sense at all.

I've never seen Anything like it.

♪♪

Narrator: the gulf of mexico.

An oil platform 200 miles Off the coast of houston,

On one of the world's Deepest drilling sites.

November 11, 2007.

A deep-sea dive team readies Their remotely operated vehicle,

Or r.O.V., for a safety Check of the rig's

Stabilizing crane wire cables,

Secured to the seabed 8,000 feet below the waves.

Above the surface, Superintendent matt dragna

Remotely controls the vehicle.

The depths that we're going to Are way too great

For a diver to access.

After 1,500, 1,600 feet,

A diver's just not A whole lot of use,

And an r.O.V. Doesn't get tired.

Narrator: the r.O.V. Passes through 600 feet.

This is as far As sunlight penetrates.

The further down they go,

The further they enter Uncharted territory.

At 7,900 feet, the depth of six Empire state buildings,

The r.O.V. Stops.

The crew think they spot Something wrong

With the anchoring Crane wire cables.

We were looking for The crane wire,

And I said, "Well, there it is."

And then I said, "There's Another one, and another one."

There was multiple crane wires.

Narrator: dragna zooms In the onboard camera.

It's not crane wires He's looking at.

These are giant tentacles.

This strange creature That's kinda crazy-looking.

It's nothing like you Would see on the surface.

It's a multi-armed organism, And it was out of this world.

Narrator: The monster from the deep Stares unnervingly at them

For 30 seconds,

Then disappears back into The inky darkness of the ocean.

Back on dry land, Dragna asks for help

To identify this alien beast.

Mardis: all of the sudden Comes this object

that looks like the head Of an ax with no handle,

with marionette strings Hanging under it.

it looks like something Out of "Independence day"

or a facehugger from "Alien."

what is it?

even after watching many hours Of video footage

down the extreme depths,

I've never seen anything Like this before.

Narrator: biologists must now Consider if the deep-sea camera

Has found an alien species.

Coming up -- an unstoppable fog Brings death to a small town.

Everything that was living In town ended up dying off.

Narrator: and marine experts Investigate

If this tentacled terror

Is a creature From another world.

Actually, "Alien" isn't A terrible word for it.

The deep ocean is almost Like a different planet.

♪♪

Narrator: deep-sea engineers Servicing oil rigs

In the gulf of mexico

Film a bizarre, tentacled beast 8,000 feet below the surface.

♪♪

Marine biologist brendan talwar Studies the footage.

There are things About this creature

That he's never seen in Any other living thing.

what's really strange About this animal is, first,

the fins on the side of the head Are really, really large.

You notice this kinda elbow Joint on the arms

And tentacles that I've never seen before.

Narrator: Its distinctive features Set it apart from any species

Known to science.

this creature is really unique.

it doesn't look like Anything else I've ever seen --

More like an alien than Any creature from a textbook.

Narrator: but aliens don't need Space ships to travel.

Asteroids are potential carriers For alien life-forms.

♪♪

This might even explain Life on earth --

A theory known as panspermia.

Panspermia is this idea That life on earth

Originated from some kind Of seeding of organisms

From other planets That seeded the earth with life.

Narrator: evidence suggests That life began on earth

Nearly 4 billion years ago.

At around this time, Millions of asteroids

And comets smashed into The planet during the period

Known as "The great bombardment."

Meteorite fragments Discovered in 1969

Contain traces of amino acids.

This leads scientists To believe that space rocks

Are carrying organic Material across the galaxy.

Did space rocks carry the dna Of this alien creature to earth

From some far-flung planet

To make a home 8,000 feet under the sea?

Scientist john farrow speculates That deep-sea conditions

Might mirror those of An alien's original home.

actually, "Alien" isn't A terrible word for it,

because the deep ocean is Almost like a different planet.

So if you look at temperature, Pressure, light,

It'll be different in the Deep ocean than it is on land.

So when you look at these Very strange creatures,

They're basically adapted To a different planet.

Narrator: Marine biologist teresa greely,

From the university Of south florida,

Examines the film.

She looks at the proportions Of the creature's body.

Greely: This particular creature,

We see A large head-like structure

And some elongated arms

That seem extraordinarily long For the size of this head.

we most closely could relate That to a group of organisms,

the cephalopods, which includes The octopi and the squid.

If we look even closer At the image

And count the number Of extensions from the body,

We count 10, And that's unique to squid.

Narrator: whatever its origin, The alien-looking beast

Has some things in common

With a group of cephalopods Known as magnapinna.

Could this be the first Ever sighting of an adult?

Researchers have found juveniles Of this species before,

But we've never Caught an adult.

So that would be my best guess.

Farrow: the deep ocean is Relatively unexplored.

And in our first forays into it,

We're discovering very weird, Alien-looking squid,

So imagine what we can find If we look deeper.

♪♪

Narrator: now, surveillance Cameras capture a toxic cloud

Engulfing an illinois town.

Knoup: you're drowning. You can't breathe.

You have a burning Feeling in your lungs.

Narrator: the killer cloud Leaves livestock dead.

The humans are next.

Pojman: if you get caught In this cloud,

Your chances of survival Are next to zero.

Pappalardo: Could it be terrorism?

Could it be an industrial Chemical that's been weaponized?

♪♪

Narrator: seward, illinois.

April 23, 2007, 7:00 p.M.

Surveillance cameras Keep a watchful eye

On a parking lot In the center of town.

All appears normal, until...

Pappalardo: people are running Away from something.

they're clearly scared.

they're clearly fleeing For their lives.

Narrator: the camera records The mass panic

As people flee the vicinity.

♪♪

And then it appears.

A fog creeping along the ground,

Engulfing everything In its path.

Pappalardo: The way that it moves,

It almost has its own Sort of life behind it.

It behaves as if it's alive.

Narrator: Firefighter mike knoup,

Based at the nearby town Of pecatonica,

Reacts to a 911 call.

Knoup: We could actually see the cloud

starting to develop On the south edge of town,

So we decided to Evacuate the community.

We needed to get them Out quickly,

So they were Running door to door

Saying you needed To get out now.

Narrator: the first, briefest Contact with the cloud

Sends firefighters running.

Knoup: It feels like you're drowning,

Kind of a burning Feeling in your lungs.

It hurts to take a breath.

Narrator: ambulances rush knoup And five firefighters

To the hospital,

Where they're treated For chemical burns.

After the cloud has Drifted through town

To destinations unknown, Seward slaughterhouse manager

Tom eickman returns to work.

He makes a terrible discovery.

The vegetation in the evacuation Area is turning a deathly color.

Everything that was living In town ended up dying.

Wherever that cloud had traveled To tended to die off.

Narrator: But there's worse to come.

Eickman had been forced To leave live animals

In the slaughterhouse,

But they weren't anymore.

we had four cattle that Were off in our back pen,

and those four cattle Were all laying on the ground.

Of the six hogs in the pen, Two of them were deceased.

Narrator: they're unfit for Human consumption.

But before destroying them, Eickman cuts one animal open

To see the effects of the cloud.

What he sees is truly chilling.

The typical hog lung is just A pink kind of mass,

And here we have these hog Lungs, all turned black.

Whatever that hog had breathed In looked like it had burned

And had killed off The lung tissue.

Narrator: material scientist Kishore hari

Thinks he's seen a gas

Before that kills like this.

this reminds me of scenes That played out in world war I,

with gases slowly creeping Over the battlefield,

Sinking into the trenches, And poisoning the soldiers.

Narrator: the incident suggests Something terrifying --

A mustard gas attack On american soil.

In world war I, mustard gas Took thousands of lives,

Victims suffering Agonizing blisters

And bleeding in their lungs.

It was german forces Who unleashed this gas,

The first true weapon Of mass destruction, in 1917.

The surveillance footage Is examined

By local historian David lawrence.

He believes, If it is mustard gas,

He knows a potential source For this world war I

Toxic terror weapon.

It might be stored just a couple Of hundred miles from seward

In a michigan town.

Lawrence: midland was The epicenter of the nation

for the production Of mustard gas.

During world war I, in midland,

Several thousand tons Of mustard gas were made.

Narrator: lawrence discovers That in 1917, a top-secret

Program code-named g-34

Produced mustard gas For use on the battlefield.

When the first world war ended,

Most of the remaining deadly gas Was dumped in the atlantic,

But it's believed some never Left the factory in midland.

They buried it there In a disposal area,

And supposedly it's still there.

Pappalardo: these things persist For decades and decades.

Those chemicals are still Waiting to be released.

It's a time bomb Waiting to go off.

Narrator: have clouds Of deadly mustard gas

Been released in the u.S.,

Threatening everything In its path?

Coming up -- fierce flashes Terrify onlookers.

Is this american city Under attack?

Luenser: it was just what looked Like a battlefield.

I thought we were being bombed.

Narrator: and experts race To solve the mystery toxic gas

Before the death toll rises.

Knoup: We did not know the severity

Of the burns to the lungs.

They had to run for their lives.

♪♪

Narrator: when a deathly fog Descends on seward, illinois,

Eyewitnesses report similar Injuries to those inflicted

By world war I killer Mustard gas.

It starts to attack your skin, And it's actually a hot,

Burning sensation on your skin.

Narrator: professor john pojman,

A chemist As louisiana state university,

Forensically examines the cloud.

He reveals that The mysterious vapor

Does not have the characteristic Yellow color of mustard gas.

Instead, he suspects the Location of the parking lot

Is a key to identifying The toxic cloud.

there are some clues In the video.

it's clearly an Agricultural area,

and fertilizers are extremely Important for agriculture.

Fertilizer Can be applied as a solid.

It could be applied In a solution

That's sprayed onto a crop.

But, surprisingly, they also Can be applied as a gas.

Narrator: pojman is aware of One nitrogen-rich gas

Which behaves like the Mysterious creeping mist

In the footage.

Ammonia.

Pojman: Ammonia is a simple molecule.

It's important because It can be used

As a source of nitrogen For plants.

That's why it's used As a fertilizer.

Narrator: experts identify an Agricultural plant close-by

As the source of the deadly Ammonia gas leak.

Deputy fire chief mike knoup Confirms

That these two people Running from the gas

Are employees of the plant.

you can see the operators Running from the cloud.

They handle ammonia on A regular basis and realize

That this was a danger.

Narrator: investigators discover The ammonia leaks

From a malfunctioning valve

As the operators pump The gas into a holding tank.

It was an 8,000-gallon tank

That was releasing all of its Contents into the community.

With that valve malfunction And the gas releasing quickly,

They had to run For their lives.

Narrator: Remarkably, no humans die

In this terrifying Toxic gas leak.

But some fear it's only A matter of time

Before another such Deadly cloud breaks free.

You would really be surprised What chemicals are around you.

There's an inherent danger That you could be in the area

Of a hazardous chemical or gas.

♪♪

Narrator: Now, terrifying flashes

Light up the texas skyline.

I knew something Was going wrong.

Something was going Horribly wrong.

Narrator: fears of foreign Military action.

Hari: there's something really Damaging happening.

These are giant explosions.

♪♪

Narrator: fort worth, texas.

May 10, 2011, 9:30 p.M.

Amateur photographer Brian luenser

Returns to his 34th-floor apartment.

A big storm is on the horizon,

And he wants to go Get some photos.

the storm kind of passed us by.

and I was kind of disappointed,

And that's when all of the Sudden the craziness started.

Narrator: witnesses watch In horror as blue flashes

Light up the city skyline

In several places at once.

Luenser: It wasn't just in one location.

I'm seeing it left and right.

I don't know What I'm looking at.

It wasn't like anything I'd ever seen before.

I couldn't really process it.

Narrator: whatever it is,

He fears the city Is in mortal danger.

I was just scared. I was in panic mode.

How could you have so many Different explosions

In so many different areas At the same time?

Narrator: Military tech journalist

Joe pappalardo analyzes The footage for clues.

He knows this part of the world

Is close to military Installations.

Pappalardo suspects the citywide Explosions in the footage

Could be some Kind of friendly fire.

Pappalardo: it's not implausible

That the military would be doing

an exercise In a downtown urban area.

they've done military exercises In fort worth before.

♪♪

Narrator: but when image analyst Conor mccourt

Studies the footage,

He believes clues in the color

Of the flashes point

To a different explanation.

Mccourt: We're getting a series of blue Flashing lights over here,

Over here, over here.

This would indicate that maybe It's electrical in nature,

Whatever's going on.

Narrator: mccourt notices Whole blocks losing power.

It's the absence of city lights That confirms his theory.

If this was an electrical Occurrence,

I might expect a blackout Where it's happening.

There is a dark spot Right in the middle.

Could be indicative Of a blackout.

Narrator: A check of records reveals

Fort worth does suffer A severe blackout that evening.

Over 4,000 people lose power.

David wallace, An electrical engineer

At mississippi state university,

Investigates If there is a connection

Between the frightening Blue flashes and the blackouts.

if you think about exotic Military weapons

that could cause damage Like we're seeing here,

There's one that comes to mind

That was really a byproduct Of the nuclear bomb.

Narrator: During tests in the 1960s,

The u.S. Government discovers

An unexpected side effect

Of a nuclear explosion.

Aside from the power Of the blast, a nuclear bomb

Also releases a powerful Electromagnetic wave,

Capable of knocking out Streetlights

And telecommunications

Hundreds of miles From ground zero.

The military calls it emp.

Emp stands for Electromagnetic pulse.

It's enough energy emitted That anything

With an electrical component

Can be burned out And rendered useless.

Narrator: u.S. Cold war warriors Realize emps can be weaponized.

Wallace discovers that, Over the decades,

The united states perfected The technology to wipe out

And erase enemy Communications.

What they've been doing Is trying to miniaturize it,

Make it more small-scale, More portable,

And be able to do The same effect

But without having A nuclear explosion.

Could this be something Like we're seeing in the video?

Narrator: coming up -- sky-fall.

It's big, it comes from above,

And it almost kills A mother and child.

They're lucky to be alive.

Narrator: and forensic Investigation of the flashes

That bring terror to texas.

Wallace: It's like a bomb going off.

And when they explode, It ain't pretty.

♪♪

Narrator: david wallace, An electrical engineer

At mississippi state university,

Investigates the cause Of a series of explosive power

Outages across Fort worth.

He devises an experiment To find out

If an emp could cause The same blue flashes

As seen in The surveillance footage.

So, what we want to do today Is build an emp.

I think we should be able to get This good little system going.

Narrator: the team sets An impulse generator

To create The electromagnetic pulse.

Designed for high-energy Physics experiments,

The generator harnesses The power stored

In multiple capacitors

And releases it In a nanosecond.

They'll direct the massive Voltage spike into this regular

Working computer.

it's gonna generate Approximately 80,000 volts.

We're gonna discharge All of this power,

And anything underneath This will experience

The full force of the emp.

Will it turn it off? Will it blow it up?

Let's find out.

All clear! Everybody out.

We're getting ready to go hot.

Let's start the system, And give me a charge of 80,000.

10,000!

All right, looking Good so far.

20,000!

30,000!

So it's gonna be A lot of juice here.

-70,000! -let's get ready to fire.

All right, We're at 80,000.

All right. 3, 2, 1, fire.

♪♪

All right, let's go see What this baby did.

Well, looky here.

The computer's off.

Everything's dead.

The computer's dead. The monitor's dead.

Nothing's coming up.

So we've obviously fried The electronic circuitry in it

With the pulse.

Narrator: wallace's emp kills The computer,

Creating a blackout Just like in the clip.

But that's where The similarities end.

The experiment creates No explosions

Or vivid blue bursts Of electrical energy

As seen in The fort worth footage.

This tends to lead me To believe it was not an emp

That we witnessed Inside the video.

Narrator: When image analyst conor mccourt

Returns to the footage,

He spots a vital clue

That may crack the mystery

Of the texas meltdown.

we have a key piece Of evidence right here

next to this blue flash.

right just to the left, We see a series of power lines

Going right up to The explosion area.

So if we go step by step, The power lines are revealed.

They're illuminated right there.

♪♪

Narrator: mccourt also spots Another clue in the footage --

A flash in the sky.

He realizes the storm Hadn't fully passed

When the explosions erupt.

there's an incredible Amount of energy

crackling through the air When these explosions happen.

Some sort of lightning strike Caused a bunch of outages

At different places Throughout the city

And that ripple effect Of multiple explosions

Along the way.

Narrator: hari concludes That a lightning bolt

Hits one of the city's Power transformers,

Generating temperatures hotter Than the surface of the sun --

More than enough To blow up a transformer,

Which in turn sets off A domino effect.

We have some sort of voltage Spike that entered

A transformer, blew it up.

And that voltage spike Just continued,

Creating a cascading effect Of transformers

Blowing up and up and up.

Wallace: It's like a bomb going off.

And when they explode, It ain't pretty.

Narrator: the electric company That serves fort worth confirms

That lightning strikes caused These fluorescent flashes.

But witnesses will never forget The intensity of the impact

It had on them.

Luenser: I was in panic mode.

My wife was, also.

She thought the world Was coming to an end.

♪♪

Narrator: coming up -- a russian Surveillance camera

Captures a terrifying near miss.

Wolshon: This is very dramatic footage.

They're lucky to be alive.

♪♪

Narrator: A russian surveillance camera

Captures a terrifying near miss.

There was no way You could have anticipated that.

Narrator: analysts Suspect a sinister force

Is behind this massive structure Falling from the sky.

Could it be some Kind of explosion?

Comes out of nowhere.

♪♪

Narrator: southwest russia.

March 19, 2016, 4:00 p.M.

A surveillance camera

Keeps watch on the town Square of labinsk

And records a horrifying moment.

♪♪

It just lands, you know, Where this woman and child

Were moments before.

Is this some kind of A natural phenomenon

That we just don't understand?

Narrator: physicist simon foster

Notices that the structure falls

From a nearby building.

He also spots a tiny clue That points to freak weather

As the roof-raising culprit.

it may not be that obvious At the street level.

What's interesting Is actually in the distance,

If you see those trees.

The trees are swaying a lot.

♪♪

Narrator: civil engineer Brian wolshon knows

Of one wind phenomenon Powerful enough

To cause the destruction In the surveillance footage.

when I see a roof Flying through the air,

that would normally make me Think of a hurricane.

Here in louisiana, Where we've had hurricanes

Like hurricane katrina And hurricane rita

And hurricane gustav,

I've actually seen roofs Torn clear off of buildings.

Those were very, Very powerful storms.

Narrator: but storm chaser George kourounis

Has firsthand experience Of weird and wild weather.

When he analyzes The passersby in the footage,

He sees a problem With the hurricane theory.

Kourounis: the curious thing About this video

Is that these people Are walking down the street,

and they're not bracing Against the wind.

they're not in some Giant windstorm.

♪♪

Narrator: physicist simon foster Turns his attention

From the elements To the roof itself.

Although the footage only Captures the roof landing,

He wonders if its shape Might hold the key.

Foster: The way the roof has come off,

It has come off In one solid piece.

That indicates to me The structure of it,

How it's built, as being a key In why it's come off.

This sounds bizarre, but the Roof was actually angled,

And it could almost Be like a wing.

Narrator: nyu physicist John di bartolo

Considers how a wing-shaped roof Might take flight.

Di bartolo: if you were to cut A cross-section

Of the airplane wing,

You would see that the upper Part is more curved

than the lower part.

that forces the air To travel faster

Over the top of the plane Than underneath.

That causes the pressure To be lower on the top part

Of the wing than underneath, Which provides a lift.

Foster: the airflow around This roof structure

Has given a huge amount of lift,

Just like a wing on a plane.

Basically, it ripped it off

And deposited it In the middle of this square.

Narrator: this raises another Intriguing question.

How can even a wing-shaped roof Take flight

On a relatively calm day?

when we think of Destructive winds,

we imagine things like Tornadoes or hurricanes.

well, yes, but under The right conditions,

you only need A wind speed of 30, 40,

50 miles an hour to cause Some tremendous damage.

and I think that's probably What's going on here.

di bartolo: if those people were Walking a little bit slower,

they would've been Under that roof,

and that would've been The end of it.