Original subtitles

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This is the most powerful electrical force on Earth.

Even hotter than the sun.

(THUNDER CRACKS)

For generations it was a mystery.

Now the latest camera technology

reveals its incredible secrets.

Lightning - violence from the skies of our raging planet.

Around the world,

lightning strikes more than eight million times every day -

a hundred times a second.

A bolt of lightning superheats the surrounding air,

causing it to rapidly expand and explode.

The shockwave creates a clap of thunder.

(THUNDER BOOMS)

Most lightning never touches the ground.

It discharges inside thunder clouds.

But when it does strike, it can do so anywhere on Earth,

delivering a trillion watts of electricity,

enough energy to power an entire city.

Running across the centre of Florida is America's lightning hot spot,

known as Lightning Alley.

Every year there are over 50 strikes per square mile,

and every year, people get hit.

On a September evening in 1999,

fisherman Dave Grillmeier had just cast his line into the lake.

Without warning,

a bolt of lightning streaked down from the cloud above him

with shocking consequences.

The rod, as you see here,

what's left of it, was about a 7ft rod.

It was obviously so hot that it burnt the epoxy away, evaporated it,

and left nothing but the carbon fibres at the end of the rod.

It wasn't just the rod that was damaged.

Dave suffered multiple burns.

But it was the condition of his clothes

that revealed the true power of the strike.

The zipper was all gone.

And I, several months later, I asked the paramedic,

'Well, was there anything stuck in me?'

And he goes, 'Your zipper was almost burned onto your abdomen -

that's how hot it got.'

This is what's left.

This is where my beeper was at, on my side.

Doesn't look too bad there

compared to what the beeper looked like when I got it back.

Dave thought his boots were untouched

until he saw strange pinholes

where the lightning had finally left his body.

I guess the electricity passed through my body

to the bottom of the shoe,

jumped over the heel and back to the ground.

Dave was one of the lucky ones.

One in every ten lightning strike victims dies instantly.

Across North America,

more people are killed by lightning than by tornadoes or hurricanes.

But there is a place on Earth that's even more dangerous.

(THUNDER CRACKS)

The heart of equatorial Africa.

Here there are more lightning strikes than anywhere else on Earth.

Dr Earle Williams

of the Massachusetts Institute of Technology

is a world authority on lightning.

Using data from NASA satellites,

he calculates that lightning strikes the Congo basin

more than twice as many times as Florida.

In some places there are over 300 strikes per square mile every year.

But lightning in this part of the world has rarely been studied.

Thanks very much.

So today, Earle is at the border between Zambia

and the Democratic Republic of Congo to witness the lightning for himself.

As darkness falls, the thunderstorms begin.

(THUNDER BOOMS)

There has been much evidence

that this IS the most electrically active place on the planet.

To be here and see it from the ground

and witness the high rates of lightning is very exciting.

Some strikes can't be seen with the naked eye,

so one way to count them is by using an optical sensor

that beeps every time there's a flash.

(BEEPING)

An average storm produces around two strikes a minute.

Here, Earle measures more than 60 a minute.

(BEEPING)

The storms here are definitely living up to expectations.

They're producing lightning at rates which are extraordinarily high.

This is really the best place to study lightning on Earth.

These are the perfect conditions for large electrical storms.

*

As the Earth is heated by the sun, it produces lots of warm, moist air.

Warm air rises.

As it gains height,

the moisture cools and condenses to form clouds.

These clouds grow and merge into larger ones,

rising all the time.

Some of the water drops become too heavy

for the updraft of air to lift.

They fall as rain.

Some are lifted by powerful air currents,

high into the cold upper regions,

where they freeze into tiny crystals of ice.

As the cloud hits the base of the stratosphere,

it spreads out sideways

to form the anvil shape typical of thunder clouds.

Dr Earle Williams of the Massachusetts Institute of Technology

studies these clouds.

The clouds that make lightning are the largest in the atmosphere.

A big active cumulonimbus cloud is about as wide as it is deep,

and they generate long anvils,

which extend horizontally in the prevailing wind, aloft.

Some ice crystals build in size to form small hailstones.

Scientists believe that as these hailstones

fall back through the rising ice crystals,

millions of tiny collisions occur.

These collisions build up an electric charge

which is stored in the cloud like a battery.

A cloud is very much like a battery,

but a battery with a much higher voltage

than your typical flashlight battery.

Not 1.5 volts, but 100 million volts.

But what scientists don't know

is exactly how this electric charge generates lightning.

What remains a major meteorological mystery

is how it is that ice particle collisions

result in the generation of lightning.

We're very much in the middle ages on that problem.

It's extremely difficult to study lightning,

since each strike lasts just a fraction of a second.

One of the best ways is to freeze the action using a camera.

David Stillings is a photographer

who patrols Lightning Alley in pursuit of electric storms.

For the last 30 years he's been obsessed with lightning.

I'd put my last few cents in my gas tank

if it meant I could go chase a storm.

His success rate is less than one per cent,

but when he does capture lightning, the results are spectacular.

(THUNDER CRACKS)

Back in 1976, this was the first one.

And when it popped out of that cloud right there

with that blue sky in there and the purple cloud - oh!

And from that point on,

lightning was everything I wanted to photograph.

This particular one, it's got so many bolts of lightning in it,

and they all happened at the same time.

This is in 2004.

The shutter couldn't have been open more than one second.

A purple sky, gold sunset -

all the neat stuff that I love to see out there.

And it all came together in one photograph! That's cool. (LAUGHS)

But before David can even begin to photograph lightning,

he has to find it.

Those two domes there

might be getting high enough to produce lightning.

And the sun is breaking through and it's going to heat it up.

The humidity's going to start.

This is cool. This is...

This has the potential of being good stuff.

David has found a thunderstorm that will produce lightning.

Now the challenge is to point his camera in the right direction.

And I hope it's a big one right there.

An average storm here

will produce a couple of lightning flashes every minute,

but it's impossible to predict where they will strike next.

(THUNDER RUMBLES)

Whoa! Whoa! I'm in the wrong spot again.

Jeez!

Whoa! Whoa!

Be later, please!

Man, listen to this thunder. Listen to this.

Listen to that.

There's another one right there. Oh, man!

This is a dangerous occupation.

Cos I got to... Oh! Oh, man!

Lightning can strike anything and anyone

up to 40km away from a cloud.

(CAMERA CLICKS)

(THUNDER CRACKS)

(DAVID YELLS DISTANTLY)

David prefers to use a traditional film camera,

so he never knows whether he's got the shot

till he gets the processed photos back.

Please tell me there's something on there.

Roll after roll after...

Oh, look, I got a streak of lightning right there. Nah.

Occasionally, David's patience pays off,

and he manages to capture the elusive phenomenon on film.

Oh, look! The channel! Yay!

Oh, man, it's...

Oh, man, is that cool?!

This is neat, man. I... Oh!

(THUNDER CRACKS)

The bottom line is, yeah, this is my addiction.

But if you have to be addicted to something, look.

A picture of a lightning strike frozen in time

can be a work of art.

But photography is also extremely valuable

for scientific analysis.

(THUNDER CRACKS)

When observed with the naked eye,

lightning appears to travel from the clouds directly to the ground.

But recent advances in video camera technology

reveal that the anatomy of lightning is much more complex.

This is the US Air Force Atmospheric Research Center

in Colorado Springs.

Here Dr Geoff McHarg

is using a super slow motion camera to capture lightning.

To do this, he needs split-second timing.

Oh, darn it.

It's a lot like fishing. You have to get lucky

and get the lightning bolt inside your field of view.

Success is rare,

but two years ago, Geoff hit the jackpot.

I was simply watching the lightning get closer,

and I kept recording it.

And I didn't know what I had until I went back and reviewed it.

For the first time ever,

Geoff had recorded the birth of a lightning bolt

in super slow motion.

When played back,

it shows a flash of light dart out of a cloud

and zigzag downward in roughly 50-yard segments.

This first stage of lightning is called a stepped leader.

You can see the stepped leader coming down here,

looking for ground, going back and forth.

You can see the torturous channel it is taking

as it divides back and forth.

As this stepped leader gets close to the earth,

it has an extraordinary effect on objects on the ground.

They respond to the strong electric field

by growing positive streamers.

These reach up anywhere

between one and a few hundred metres above the ground,

as seen in these rare photographs.

Finally, when a stepped leader and a positive streamer meet,

the electric charge can drain to earth,

resulting in the blinding flash of light we call lightning.

The entire field of view lights up.

That's the main part of the lightning strike

that your eye would catch.

(THUNDER CRACKS)

The new generation of cameras has enabled scientists

to record a strike that lasts just a fraction of a second.

(THUNDER CRACKS)

They then play it back over 200 times slower

to analyse its details.

These super slow motion images show the stepped leader

making a connection with the ground.

The entire charge then drains from the cloud above,

seen as a series of pulses.

Scientists are now just beginning

to unravel the mysteries of lightning.

New research has revealed that heat and humidity

can have an effect on the frequency of lightning storms.

(THUNDER CRACKS)

*

Tampa, Florida, is the lightning capital of the United States,

with more lightning than anywhere else.

Scott Steiger from State University of New York

believes the city attracts lightning

because Tampa is an urban heat island.

An urban heat island is caused by the fact

that a city area has a lot more impervious surfaces

of asphalt and concrete

that absorbs a lot of the sun's solar radiation.

That energy gets re-emitted and warms the air in the city.

A city can be as much as 15 degrees warmer

than the surrounding rural areas.

As the warm air rises,

it creates strong upward convection in the atmosphere over the city.

This urban heat island can cause more thunderstorms

as it develops a convergence zone over the city,

which helps to lift the air and initiate more thunderstorms.

The creation of thunderstorms means lightning is inevitable.

Especially cities in warm, humid climates,

like Tampa Bay, Florida, and Houston, Texas,

are very capable of producing more thunderstorms

and more lightning, which is more dangerous to the public.

Scientific research has recently produced evidence

that lightning doesn't just come down from above.

It also streaks up high into the sky.

Here in Rapid City,

scientist Tom Warner has been using high speed photography

to uncover a previously hidden world of lightning.

We're seeing things in such a way that we've never seen before.

Using a battery of cameras,

he's managed to capture some astonishing images

which show lightning travelling not from cloud to ground

but shooting upwards.

This extraordinary form of lightning

has been known about since the 1930s,

but these pictures have finally confirmed its existence.

This is the first time that mankind

has seen upward lightning in such detail

as we're seeing right now.

Our understanding of physics relating to these upward flashes

is increasing immensely.

Tom has observed that upward lightning

is triggered by a nearby cloud-to-ground lightning strike.

In this image a lightning strike produces a bright flash of light.

In under a second, it initiates the formation of upward leaders

from two radio masts.

Why this happens is still a mystery,

but Tom's theory is that the lightning strike

causes large amounts of electric charge

to build up around the top of a tall structure,

and this charge leaps up and connects with a cloud above.

You'll see a delay between when the flash takes place

and then the leader is shot up from the tower tip and goes upward.

The images Tom has filmed over the last few years

have astounded the world of lightning science.

This mysterious lightning

would never have been seen without state-of-the-art technology.

(THUNDER RUMBLES)

But to see one of the greatest lightning displays on the planet,

the only equipment you need is your eyes.

Here on Venezuela's Lake Maracaibo,

a team of scientists from the University of Zulia

are setting out in search of

the region's legendary Catatumbo lightning.

Unusual conditions in this area create a unique kind of lightning.

Methane gas bubbles up from rotting vegetation

in the swamps and rivers.

And Lake Maracaibo's oilfields also produce methane as a by-product.

It all accumulates in the atmosphere above the marshes.

As night falls,

the scientists are hoping for an electrical storm

so they can study the extraordinary effects of the gas.

Methane is lighter than air.

As it rises up into the clouds, it feeds the storm,

creating brighter, much more colourful lightning.

But lead scientist Professor Angel Munoz and his team

think there may be more to Catatumbo lightning than meets the eye.

Catatumbo lightning leaps from cloud to cloud,

and is much more powerful than cloud-to-ground lightning.

(THUNDER RUMBLES)

On average, it can be seen 200 nights of the year

for up to ten hours a night.

This display is so colossal, it's visible 160km out to sea.

For centuries, sailors used it for navigation.

It was known as the Maracaibo Lighthouse.

A lightning storm can be spectacular from a distance,

but up close, lightning can be deadly.

During a thunderstorm,

the most dangerous place to be is in a wide open space...

...including any large expanse of water.

And it's true that sheltering under a tree is a bad idea.

Lightning can turn tree sap into superheated steam,

making the tree explode in a shower of potentially deadly splinters.

Lightning can also travel down telephone lines.

There's a very scary warning sign that you're in danger.

If your hair stands up, you've just become a positive streamer.

And coming down from that cloud

is a negative leader that, if you don't do something,

when they connect, you've just become a bolt of lightning.

If this happens to you, the best thing to do

is to quickly crouch down on the balls of your feet.

(LOUD CRACK)

Student Carolynn Nath had no warning she was in danger.

She was making her way to class

at the University of South Florida in Tampa when lightning struck.

(THUNDER CRACKS)

I heard a loud, loud crack of thunder,

and within a second, I saw a light.

Basically, the corridor in front of me of palm trees

was an overexposed picture.

And I felt the electricity start going through my entire body.

I could feel it, every ounce, every inch of my body.

My muscles expanded, they contracted very tightly.

And every nerve, it just...

I could feel that pressure going through my entire body.

The after-effects were devastating.

Everything was completely swollen. My skin was lobster red.

It was basically like I had a very, very severe sunburn.

So, afterwards, everything... all my skin peeled off.

(THUNDER CRACKS)

A lightning flash contains up to 200,000 amps...

...but it takes just one-tenth of an amp to kill a human being.

(SIREN WAILS)

So how do victims survive a lightning strike and live to tell the tale?

Doctors at the University of Illinois have been trying to find the answer.

Professor Mary Ann Cooper

is an expert on what happens when lightning strikes.

When lightning attaches to a person,

the vast majority of the energy goes around the outside of the person

rather than through them.

Instead of striking vital organs,

the charge flows through the moisture on the skin and down to the ground.

It can leave behind scars called Lichtenberg marks.

As it's going around the outside,

it may turn the rainwater or sweat the person has on them into steam.

Sometimes, the build-up of steam in clothing or shoes

can have explosive consequences.

You may have heard about people in explosions

blown out of their shoes -

that's what we see sometimes with lightning as well.

Because that sweat or the water expands tremendously

so that we actually see more damage to the inside of footwear

and sometimes to clothing than we see to the outside of it.

A lightning strike can cause cardiac arrest, but this is rare.

MARY ANN: The vast majority of people survive lightning injury,

although they may have permanent problems,

including damage to the nervous system.

One survivor, Pam Cooper,

is still suffering from the damaging power of a strike.

I was just a mom sitting on the beach with my book,

minding my own business, doing nothing extraordinary,

and my life was changed forever by lightning.

(THUNDER CRACKS)

I don't remember the actual event of being struck.

It's through my friends and family that I know second-hand

what exactly happened to me.

That day, Destin Beach in Florida was hot and sunny.

My family says that they heard a large clap of thunder, lightning.

Everyone else was starting to scurry and pick up their belongings

because of the lightning strike being so close.

I was sitting with my feet in the sand,

and the lightning struck the sand and then came up through my feet.

(DISTANT SIREN)

Pam was rushed to the hospital with extensive burns.

Five years later, she still suffers from mobility problems

and short-term memory loss.

Being struck by lightning is very similar to a computer crashing,

because, on the outside, I look fine.

But on the inside, my circuitry's all messed up.

Pam's experience could happen to anyone,

so it's vital to know exactly what to do

to protect yourself from a lightning strike.

*

When a thunderstorm forms, people's lives can be at risk.

We tell people, 'When thunder roars, go indoors.'

What we mean is 'Seek a safer shelter.'

If you're ever in a thunderstorm,

one of the safest places to be is in a closed vehicle.

Many people believe the rubber tyres on a car will keep them safe,

but that's not true.

It's the car's metal body that provides protection...

...as this high-voltage experiment will demonstrate.

A Tesla coil is the lightning simulator,

an electrical transformer that discharges

three-quarters of a million volts of electricity.

Dr Lisa Lazareck is an electrical engineer

who's willing to sit in a car underneath the coil

to prove that its metal body will protect her.

The electrical charge striking this car is going to conduct

around the outside surface of the enclosed body,

so I should be fine as long as I don't touch the metal of the car.

But it's one thing to talk about the theory,

and it's another thing to put it into practice.

So I guess I'm ready.

The electrical charge flows around the metal body of the car

and discharges harmlessly to the ground.

I'm fine. The theory has worked as expected.

My feet are slightly tingling,

and, because I was nervous, my hands are still clamped together.

But other than that, I'm fine.

The experiment has just proved the rule of physics

that an electrical charge like lightning

will always travel around the outside surface of an enclosed metal body.

That's why passengers are unharmed when a plane is struck by lightning.

This incredibly rare footage of a plane flying into Sydney Airport

shows a dramatic strike.

No-one on board even knew they'd been hit.

And this video captures another

as a plane takes off from an airport in Japan.

Once again, the passengers had no idea what happened.

On average, every commercial aircraft is hit once a year.

Besides suffering a direct hit from a lightning bolt,

the biggest threat to life is when lightning triggers a fire.

During the summer of 2008,

an unusually high number of lightning strikes

set large areas of California on fire.

One single storm unleashed up to 5,000 strikes...

...igniting more than a thousand individual fires.

The flames destroyed dozens of homes.

In a lightning-prone area,

living in houses built among trees carries a high risk.

But though lightning fires

can destroy property and devastate forests,

they can also have a positive effect on the landscape.

Nature has evolved a way to work in harmony with lightning fires,

and even depends on them to renew life.

Here, in the Australian outback, such fires are a common occurrence.

Jeffrey Lee is a park ranger charged with looking after the land.

He welcomes the fires because they clear the ground

and encourage the regrowth of edible plants, or bush tucker.

Many plant species

have evolved to colonise the areas these fires lay bare.

and some seeds actually need fire to germinate.

Lightning also helps produce vital plant fertilisers.

(THUNDER CRACKS)

At its peak, the temperature of a lightning bolt hits 50,000 degrees,

burning the air.

In the heat, nitrogen and oxygen react together to create nitrates.

These rain to the earth and provide nutrients for plants.

Scientists have now discovered that lightning may also be playing a part

high in the Earth's atmosphere.

When these bizarre images were taken from above the earth,

they took scientists completely by surprise.

They showed huge bursts of light

flashing over the top of electric storms.

Called sprites, they were first photographed in 1989.

Since then, scientific projects around the world

have joined the hunt for these elusive phenomena.

In 1997, New Zealand scientist Professor Richard Dowden

arrived in Australia's Northern Territory

on a quest for sprites.

Richard wanted to be one of the first to capture them on camera.

He came here with his scientific team to Beatrice Hill,

60km east of Darwin.

(THUNDER CRACKS)

This region is home to some of the biggest thunderstorms on Earth.

But Richard wasn't interested in regular lightning bolts.

He was chasing sprites, which appear directly above thunderstorms.

Beatrice Hill was a perfect place to spot them,

because you need a clear view of the top of a thundercloud

from a distance of nearly 100km.

Even then, the sprites are hard to see with the naked eye

because they're only visible for a few milliseconds.

So Richard made a special modification

to his standard amateur camera.

The big change was this thing in front of it,

which is an image intensifier.

These are used by the military all over the world.

Rather hard to get, the ones which are very sensitive.

This one here actually came from Russia, from the Russian military.

Richard and his team waited night after night,

taking turns manning the camera.

After nearly two weeks, they finally had a breakthrough.

Well, on the night we got those sprites, it was really a big thrill.

But we didn't know what was there

until we ran the tapes back out of the camera.

The tapes reveal these flickering images of sprites

speeding through the atmosphere

at more than one-tenth the speed of light.

That was a fantastic thing.

I don't think we got any sleep, any more sleep that night.

Scientists remain mystified by the first fleeting sightings of sprites.

But just two years later,

Dr Geoff McHarg of the US Air Force Atmospheric Research Academy

made another breakthrough.

He managed to record sprites using an image intensifier

on the front of his super slow motion camera.

It was probably the most fun I've actually ever had taking data.

It was just great.

We took data all night long.

We recorded pretty much every tape that we had.

The tapes revealed an incredible variety of sprites.

The scientists have since given them names.

What we're looking at right now is a jellyfish sprite,

and the first thing you'll see is, they're very large.

They may be 30 miles tall, 30 miles wide.

Just think about that. That's almost from Colorado Springs to Denver.

Then there's the extraordinary carrot sprite.

It physically looks like a carrot,

with the upper part being like the leaves of a carrot

and the downward tendril that we call it

going like the stalk of the carrot.

Geoff also captured the 'C' or column sprite.

Here we have three of them side-by-side.

And the motion is pretty much all down,

hence the name 'column' or 'C' sprite.

Around the world, as many as ten sprites

could be shooting up from the clouds every minute.

Scientists now know that sprites are large-scale electrical discharges

that make the air above them glow

in a similar way to a fluorescent light bulb.

But it will take a lot more research

before we truly understand these electrical phenomena.

(THUNDER CRACKS)

Even though the serious study of lightning

began over two centuries ago,

scientists are still struggling to work out

what guides lightning's path

or why it chooses to strike in one place over another.

We've learned a lot about lightning in a few hundred years,

but there is still a major meteorological mystery.

What we do know

is that lightning has an incredible capacity for destruction,

and it can never be controlled.

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