Snowflake Hunter Scours the Earth to Study Crystals

It was the middle of January, the temperature had dipped to 40 below, and a peculiar phenomenon known as ice fog was drifting across the desolate landscape near Fairbanks, Alaska. That's the kind of weather that makes sane men seek cover, but Kenneth Libbrecht was, well, feeling a little flaky.

"I loved it," he says, recalling one of dozens of trips that have taken him from his home in sunny Southern California to some of the coldest places on the planet.

That's because Libbrecht's passion is snowflakes. He is undoubtedly the world's foremost expert on the subject, and there's nothing frivolous in his effort to study and photograph the ice crystals that form snowflakes.

Libbrecht is a professor of physics at the California Institute of Technology, and the creator of one of the most popular Web sites on the Net, which draws about 2 million visitors a year. The site, SnowCrystals.com, is, of course, all about snowflakes.

"I got into it from the science end," Libbrecht says. His main field of interest is crystals, everything from diamonds to semiconductors, and how materials condense into solid structures. It's a booming field because crystals form the heart of many a gizmo these days, including the computer that was used to produce this story.

"I was looking at how crystals grow and thought snow crystals would be an interesting subject to dive in to," he says. Ice is abundant, easy to work with, and it has one terrific asset.

"It's very cheap," says Libbrecht.

"So I started reading about snowflakes, and it was one of those things where one assumes that everything is known about this, and I was surprised to discover that there are a lot of things that are not even remotely understood."

Snowflakes form differently, depending on the temperature. At minus 30 degrees, for example, snowflakes become columns of ice crystals, and at three to 10 degrees above zero, they take the shape of stars. Why should temperature be the determining factor?

"Nobody knows," Libbrecht says.

Libbrecht has built a system that makes snow crystals in his lab, which allows him to control all the variables, and that's one of the questions he's trying to answer. But if he's getting close, he's keeping it to himself.

"It's not one of these things where you wake up in the morning and have a eureka moment," he says.

One of the most interesting findings to come out of his research is something he calls branching instability. He has demonstrated that, like much in nature, snowflakes grow partly through instability.

"A lot of nature is driven by instability," he says. The complex flapping of a flag in the wind, or the complex motion of ocean waves breaking on a beach, are complexities produced by instabilities in nature.

He has found that a similar process occurs in the growth of snowflakes. A snowflake may begin as a simple hexagonal prism, but as it grows the corners stick out farther and grow faster. The faster growth causes the prism to sprout six arms, each of which is influenced by wind in the clouds and changes in temperature as the snowflake rises and falls.

As it grows the structure "gets thinner and thinner, and there's an instability once you get a thin plate," he says. That, in turn, leads to an even more complex structure as the flake continues to grow.

"A lot of crystal growth, especially pattern formation, is driven by instability," he says, and that doesn't just apply to snowflakes.

It's possible that learning exactly how snow crystals form and grow may be helpful in other areas of research.

"A lot of material science is done in what I call enlightened trial and error," Libbrecht says. "For instance, people have grown diamond crystals for 50 years, but after 50 years of effort, nobody can grow really large ones. They are slowly getting bigger, and they are slowly getting closer to gem quality, and it's mostly trial and error, trying different ways to grow them.

"If you learn something from another crystal, like ice, maybe you can become more enlightened, and trial and error moves more quickly."

Libbrecht is in it for the science, but the question he gets most often has been around for three quarters of a century. Is every snowflake unique?

That question was first suggested by a Vermont farmer who, like Libbrecht, became obsessed with snowflakes. Wilson Bentley attached a camera to a small microscope and spent years taking photos of flakes of snow.

By 1931 he had captured 5,381 photos of snowflakes, and he noted that they were all different. Thus, the expression that no two snowflakes are alike.

Was he right?

It depends on what you mean by alike. Certainly many snowflakes look alike, at least on the surface. But are any two snowflakes exactly alike, both in molecular composition and structure?

That, says Libbrecht, is "very, very unlikely." The chances of two flakes having exactly the same structure, and exactly the same molecules arranged in exactly the same sequence is about as unlikely as a snowball's chance of surviving in a very warm place.

He's sure of that, but there's still lots to learn out there, so Libbrecht will continue to lug his equipment around the world, capturing more photos. The hardware consists of a microscope and a camera, mounted in a carry-on suitcase, which sometimes drives security guards up the wall when he tries to pass through the boarding gate.

So he will spend lots of days and nights out in the cold, where he has at least a slight chance of getting his photo before his chosen flake evaporates as he continues to probe a world that is far more complex than most of us thought.

"That's what makes it interesting," he says.

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