Sextillions of snowflakes fell from the sky this winter.
That’s billions of trillions of them, now mostly melted away as spring
approaches.
Few people looked at them closely, one by one.
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Kenneth Libbrecht, a professor of physics at the California
Institute of Technology, has spent a quarter-century trying to understand how
such a simple substance — water — could freeze into a multitude of shapes.
“How do snowflakes form?” Libbrecht said during an online
talk Feb. 23 that was hosted by the Bruce Museum in Greenwich, Connecticut.
“And how do these structures appear — and just, as I like to say, literally out
of thin air?”
One of the people intrigued by Libbrecht’s snowflake
research and photography was Nathan Myhrvold, a former chief technology officer
at Microsoft who has since pursued projects in myriad scientific disciplines,
including paleontology, cooking and astronomy.
Myhrvold, an avid photographer, first met Libbrecht more
than a decade ago, and in the spring of 2018, he decided he wanted to take
pictures of the intricate frozen crystals himself. He recalled thinking, “Oh,
we’ll just throw something together, and we’ll be ready for the winter.”
But, as with many of his projects, things were not as simple
as Myhrvold planned.
“It turned out to be massively more complicated than I
thought,” Myhrvold said. “So it took 18 months to build the damn thing.”
The “damn thing” was the camera system for photographing
snowflakes. He wanted to use the best digital sensors, ones that captured 1
million pixels. “The real snowflake is very, very fragile,” he said. “It’s
super intricate. So you want high resolution.”
But that kind of sensor is much larger in area than the
images generally produced by the lenses of microscopes, a result of decisions
that microscope manufacturers made close to a century ago.
That meant he needed to find a way to stretch the microscope
image to fill the sensor.
In his tinkering, “I came up with a custom optical path that
will actually allow it to work,” he said.
Then there is the housing for the optics. That is typically
made of metal, but metal expands when warm and shrinks when cold. Moving the
apparatus from the warm indoors to a frigid balcony where he would collect the
snowflakes “would screw up the whole microscope,” Myhrvold said, making it
impossible to keep everything in focus.
Instead of metal, he used carbon fiber, which does not
appreciably expand or shrink.
Myhrvold also found a special LED, manufactured by a company
in Japan for industrial uses, that would emit bursts of light 1/1,000th as long
as a typical camera flash. This minimizes heat emitted from the flash, which
might melt the snowflake a bit.
To look at something under a microscope, a specimen is
typically placed on a glass slide. But glass retains heat. That also melts the
snowflakes. So he switched from glass to sapphire, a material that cools more
readily.
By February 2020, he was ready. But where to find the most
beautiful snowflakes to photograph? At first, he thought he could just head to
a ski resort town — perhaps Aspen or Vail in Colorado or Whistler in British
Columbia.
But these places were not cold enough.
“Powder snow that a skier might like to ski through is, in
fact, pretty much powder,” Myhrvold said. “There’s not a lot of beauty in those
things.”
When temperatures are just below freezing, the snowflakes
are generally simple hexagon plates. At about 20 degrees Fahrenheit, the
prevalent shape is hexagonal columns. It is between 15 degrees and -5 degrees
Fahrenheit that the archetypically beautiful snowflakes usually form.
At these temperatures, the points of the hexagon grow into
branches. The branches then spawn other branches and smaller hexagonal plates.
Slight variations in the temperature and humidity affect the growing pattern,
and the conditions are constantly changing as the snowflake falls toward the
ground.
“Because it has this complicated path through the clouds, it
gives a complicated shape,” Libbrecht said. “They’re all following different
paths, and so each one looks a little different, depending on the path.”
Thus, to find the beautiful snowflakes, Myhrvold went north,
much farther north. He and a couple of assistants lugged about 1,000 pounds of
equipment to Fairbanks, Alaska; Yellowknife, the largest community in the
Canadian Northwest Territories; and Timmins, Ontario, about 150 miles north of
Lake Huron.
A month later, the coronavirus pandemic put the endeavor on
hiatus. But Myhrvold was able to take what he calls the highest resolution
images of snowflakes ever.
That claim has irked others in the snowflake world,
including Don Komarechka, a Canadian photographer who takes a decidedly lower
tech approach. He uses a store-bought digital camera with a high-power macro
lens. He does not even use a tripod — he just holds the camera while the
snowflakes sit on a black mitten that his grandmother had given him.
“Incredibly simplistic,” Komarechka said. “It’s so
approachable for anybody with any camera.”
He said of Myhrvold’s custom-built system: “I think it’s a
little over-engineered.”
Komarechka also takes a different approach to illumination,
using light reflected off a snowflake, while Myhrvold’s images capture light
passing through. “You get to see surface texture and sometimes beautiful
rainbow colors in the center of a snowflake,” Komarechka said.
The rainbow effect is the same as what you see in soap film,
but the colors are “often much more solidly displayed than you would see in a
soap film or anything else,” he said. “It’s almost psychedelic colors, almost
looking like a tie-dye T-shirt.”
To counter Myhrvold’s claims, Komarechka took an image that
he says was even higher resolution. Myhrvold responded with a lengthy rebuttal
explaining why his images were, nonetheless, more detailed.
In practical terms, Myhrvold’s images are sharper when
printed on paper at expansive sizes. They are available for purchase at sizes
up to 2 meters by 1.5 meters.
“In that very narrow sense, yep, that’s what Nathan is
claiming, and he’s not wrong,” Komarechka said.
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