National Geographic: Cyclone! Page #2

---

and remain a cornerstone of

tornado science.

Although they occur

around the world,

three out of four tornadoes streak

the skies over the United States.

They favor the springtime, and the

warm hours between noon and sunset.

We say a tornado "touches down".

It actually sucks in air from

near the ground

and carries it upward in a spiral.

Most range from 150 to 1200 feet

in width,

and travel over land at about

The funnel is often hollow,

a tube of condensed water vapor

that takes on the color of dust

and debris.

In North America, most tornadoes

rotate counterclockwise.

Perhaps one in a thousand spins

in the opposite direction.

Twisters appear in many guises.

They can bring to mind

the snapping of a bullwhip...

or the delicate dance of ghosts.

A single storm can spawn several

distinct funnels

- a grouping referred to as a

"family."

For all their fury,

most tornadoes are short-lived.

Many last only minutes.

To the scientists who would study

them, they are elusive prey.

How to penetrate the twister's

secrets?

Aiming weather balloons and

instrumented rockets into tornadoes

have yielded limited results.

All right. Three. Two. One.

Fire!

There! Perfe...

No.

In the 1980's, researchers at the

National Severe Storms Lab

tested the "totable tornado

observatory", nicknamed TOTO,

after Dorothy's dog

in The Wizard of Oz.

This four-hundred pound package

of sensors

was to record what no human can

even approach

without risking life and limb.

But predicting the path of a tornado

proved to be nearly impossible.

TOTO had one close call,

no direct hits.

For now, the safest way to see

inside tornadoes

is to probe them from afar with

Doppler radar.

Like an x-ray of a storm,

the system displays wind speed

and direction.

In 1981, scientists first detected

the spiraling signature of

a tornado on Doppler radar.

Today, the system is used to

issue warnings to the public.

Still, we're not exactly sure

why twisters form at all.

For Howard Bluestein,

Professor of Meteorology

at the University of Oklahoma,

there's only one way to find out.

Satellite pictures are nice.

Radar pictures are nice.

But you need to look out the window

and see the clouds at a

very very fine scale

to get a feeling for

what's happening.

I don't understand

how one can study a phenomenon

without actually experiencing it.

Seeing it or feeling it

or tasting it.

To me, that sets everything

in motion.

That makes me want to understand

why it's there,

what causes it,

what's gonna happen to it.

They just issued a tornado warning

for right where we are.

Every spring, Bluestein exercises

two considerable talents:

chasing tornadoes, and measuring

them with the latest technology.

Portable Doppler radar is like

a meteorological magnifying glass.

It allows Bluestein to measure

wind speed in very fine detail,

in specific regions of a tornado.

Okay, we better get going quickly.

That thing is starting to form

a nice funnel.

Actually, hold it.

Hold it. Hold it!

Can you turn it on?

It is starting to form a funnel

and it's not that far away.

I'm on the left side of that

tight circulation.

Bluestein's success rate is

better than most storm chasers'

The funnel cloud is just

to our north, northwest.

We're packing up the radar...

He estimates one

in nine expeditions ends

with an encounter.

OK, tornado is crossing the path

of the radar.

Debris in the air.

Strong tornadoes almost always form

under the southwest edge of a storm.

Bluestein plots his course

accordingly,

and tries to place his team roughly

two miles from touchdown.

Center it right on the funnel!

Oh, what a classic!

Should I go to FM?

Only if you have a good CW signal.

We're detectives.

We're looking for lots of bits

of evidence.

And the more pieces of evidence

we have,

the more likely it will be

that we'll be able to solve

the puzzle of why tornadoes form

and what's their structure.

April 26th, 1991.

Bluestein and his team track

the outbreak

that will ravage Andover, Kansas.

A spectacular funnel stops them

in Red Rock, Oklahoma.

Their Doppler radar will capture

the fastest windspeed on record:

nearly 280 miles an hour.

In the heat of the chase, even

Bluestein can miss a beat.

Let's get out of here fast,

let's go!

For less frenzied fieldwork,

Bluestein turns to these hunting

grounds:
the Florida Keys.

August, 1993.

The National Oceanic and

Atmospheric Administration,

and the National Geographic

Society

reunite Bluestein

with Dr. Joseph Golden,

expedition chief scientist.

As a graduate student,

Bluestein once joined Golden to

explore the skies over Key West.

This expedition marshals

state-of-the-art scientific

and photographic technology.

The quarry?

A phantom twister that haunts

these tranquil waters.

In 1967, on a vacation trip,

Golden took a sightseeing flight

over the Florida Keys,

and had a chance encounter with

one of our atmosphere's most

startling apparitions.

Since that time,

he has become the world's leading

expert on waterspouts.

Our knowledge of these ethereal

ribbons was once based largely

on mariners' accounts.

Golden first emphasized their

similarities to tornadoes.

Though usually smaller than a

twister over land.

They form in gentler weather

than most violent tornadoes,

allowing close inspection.

Smoke flares will help visualize

airflow near the sea surface.

For Bluestein, this is an

unparalleled ringside seat.

When we're out in the great

plains looking at tornadoes,

we cannot see what's happening

right at the ground very clearly,

nor can we see what's happening

at cloud base extremely clearly.

The perspective that we get

from the helicopter

in that we can look down

at the sea surface...

and see the effect of rotation

at the ground level

and also be at cloud base

and practically kiss...

the condensation funnel

that's right outside the window

is really spectacular.

Ultimately, the ghostly waterspout

may reveal the hidden forces

that trigger tornadoes.

Joe, I guess climatology works.

That was incredible!

Other whirling winds demand a

more lofty vantage point.

Book a seat on the Space Shuttle for

the perfect view of these monsters

- over 500 miles wide,

and some ten miles high.

Creatures of the sea,

they breed in the warm oceans of

the tropics.

Depending on their birthplace,

we call then 'cyclones',

'typhoons', or 'hurricanes'.

These giants can stir up

more than a million cubic miles of

the earth's atmosphere every second,

and travel across an ocean at up to

Yet they have humble beginnings.

In the summer and fall,

the sun heats vast stretches of

tropical ocean

to over 82 degrees Fahrenheit.

Warm, moist air rises over these

hot spots,

forming bands of thunderstorms.

Upper level winds push storm

systems westward,

as surface winds spiral into the

low pressure beneath the clouds.

Occasionally,

one such spinning wheel

of thunderstorms gathers strength,

Rate this script:0.0 / 0 votes