[WIND]
NARRATOR: Ever since the Victorian era, snowflakes have
been revered as perfectly symmetrical six-sided crystals.
Believed to be as perfect and pure as the heavens from which
they descend. But what if this divine image just…melted away?
♪ MUSIC ♪
It's 1885 in Vermont's wintry terrain. 20-year-old Wilson
Bentley is fascinated by snowflakes. So he attaches
a camera to his parents' microscope to capture
a photo of one.
After countless attempts, he finally gets a clear picture.
Thousands of pictures later and Bentley's collection is
dominated by what comes to be our iconic view of snowflakes –
each perfectly symmetrical yet unique. Bentley even coins the
phrase "no two snowflakes are alike."
Across the Atlantic, German meteorologist Gustav Hellmann
and his associate Richard Neuhauss are photographing
snowflakes as well.
However their photos reveal something entirely different.
While each snowflake is unique, many are irregularly shaped.
Imperfect.
It's said that Hellmann accused Bentley of altering certain
photos. Bentley countered that any alterations were to remove
dust particles or debris from the snowflake photo to show
the flake as true to nature as possible.
It's now present day in the snowy mountains of Utah.
An area that thrives on winter tourism.
It's here that NSF-funded engineer Cale Fallgatter and
atmospheric scientist Tim Garrett have revolutionized the
process of capturing photos of snowflakes. To better study
their fleeting existence.
Predicting how winter storms will affect us depends on
how we measure what falls out of them. But current
methods are imprecise.
Fallgatter and Garrett have developed a high-speed camera
system specifically designed to provide the clearest pictures
ever of freefalling snowflakes.
They call their system the Present Weather Imager, the
PWI. Composed of a single industrial grade 1.3 megapixel
camera and a built in computer, the PWI uses an infrared motion
sensor to photograph single snowflakes as small
as 100 micrometers.
A fleeting moment in time exists to gather data on
a single snowflake. In the clouds…too soon. On the
ground…and it's too late. So the PWI doesn't isolate or
disturb the snowflakes. It waits for the perfect time,
photographing them as they fall to the ground.
Mid-air. Unaltered.
Providing data on a snowflake's size, shape, orientation and
even the speed at which it falls. And if researchers
understand all of this…they can determine exactly what type of
snow formed in the clouds above.
Snowflakes have brief but complicated lives. They start
when a super-cooled water droplet freezes around a speck
of dust. This process alone results in Wilson Bentley's
famous six-sided crystal. But it's difficult to discover one
of these on the ground…
Because as a snowflake falls, it collides and freezes with other
water droplets. A process known as "riming," resulting in a
little ice pellet called a "graupel"…the hard packing snow.
If a snowflake manages to dodge these water droplets, it will
likely later collide with other snowflakes to form something
entirely different. An "aggregate"…
the light fluffy snow.
So the PWI (Present Weather Imager) photographs falling
precipitation and then classifies every single photo.
Aggregate, graupel, sleet, ice, rain.
Each type of precipitation affects road conditions
differently. Projecting these, especially around the freezing
point, is a current problem. But with the PWI's data, local
transportation departments could issue better weather warnings.
With the potential to save lives.
The PWI also captures nature in its purest form.
Common among snowflake photographers, Bentley hand
selected the most attractive snowflakes to photograph
and rejected those less photogenic.
What Bentley and many others did was spark the public's
fascination and curiosity about snowflakes, leading to the PWI's
modern day answer to how to capture a snowflake.
♪ MUSIC ♪