The Slick Science of Making Olympic Snow and Ice

 Behold, the unsung hero of the Winter Olympic Games: ice. (Vadym Cherenko / Alamy)

Behold, the unsung hero of the Winter Olympic Games: ice. (Vadym Cherenko / Alamy)

No one thought Brian Shimer had a chance. At two months shy of 40, the American bobsledder arrived at the 2002 Salt Lake City Olympics with four winter games under his belt, but no Olympic medals. So when his team zipped through the winding track and earned that long-awaited bronze, everyone was astonished—not least of all Shimer. ″I don’t know what brought us down the hill so fast,″⁣ he told The New York Times. ″The electricity in the air, the crowd waving and yelling.″⁣

Certainly the crowd’s support—along with the team’s intense training and Shimer’s precise turns—were crucial. But one unsung hero of winter sports also played starring role in the team’s triumph: the ice.

In a sport when just hundredths of a second separate the winners and losers, every friction-inducing bump or groove matters. And ice wears down overtime, so Shimer and his team’s 17th start position could have easily been a disadvantage. Yet the sled finished in fifth, setting them up for the bronze. “You can’t do that if the ice is not consistent,” says Tracy Seitz, managing director of the Canadian ice track known as the Whistler Sliding Centre, which touts the “fastest ice track in the world.” Seitz would know: He was also one of Salt Lake City’s so-called “Ice Masters,” the experts tasked with the challenge of creating the ideal ice tracks for world-class athletes.

There’s a lot more to making ice than meets the eye. On a molecular level, the snow and ice of Olympic courses is exactly the same stuff that makes snowmen, blocks off your doorway and sends unsuspecting bystanders careening down driveways. All frozen water consists of molecules arranged in a hexagonal structure similar to a honeycomb. But the ice coating the sinuous sliding tracks for bobsled, luge and skeleton, or the firm, flattened snow of a ski course are precisely shaped and conditioned over the months leading up to the games, optimizing the properties of these frosty forms of water.

“It’s not just a hunk of ice like you’d normally think of, like ice cubes sitting in your freezer,” says Kenneth Golden, a mathematician at the University of Utah who studies the structures of ice. “It’s a much more fascinating and complex substance than people would normally think.”

Ice, Ice, Maybe

The first step for building any ice rink or track is to purify the water to remove dissolved solids like salts and minerals. Such impurities don’t fit in the regular hexagonal structure of ice that forms as water freezes. The same property can be seen in sea ice, Golden explains, which excludes the salt of the ocean water as it freezes, creating a plume of extra salty liquid below the ice. But in a rink or track, impurities collect between crystals or are shoved to the surface, creating slight weaknesses in the ice. As Seitz says, “the more pure the water is, the more dense the ice slab would be,” which translates to a more consistent surface.

The quality and purity of ice is so important that a special position—the Ice Master—has been created to ensure its viability. Forget sculptors who make intricate ice sculptures; Ice Masters shape ice into some of the most impressive structures on earth. At least a year in advance of the Games themselves, they spray hundreds of paper-thin coats of this ultrapure water on a concrete course or rink, which is chilled by an embedded refrigeration system for rapid freezing. It takes around five days of non-stop work to lay the frozen track for a bobsled run, says Seitz.

This process prevents the formation of frost layers, which form when humid air freezes over the icy surface. Frost layers can trap air bubbles in the ice, which can work their way out as tiny pockmarks. “We don’t think of it [ice] as fluid, but it is very much so fluid, and it’s moving all the time,” says Seitz. “Those layers of air in the ice will create weaknesses that can break out and create inconsistencies in the ice surface.” For a bobsled, one tiny pockmark can cause a sled to bounce, perpetuating the problem. “One bump creates two bumps creates three bumps, and on and on and on,” he says.

Other ice-based sports like hockey, ice skating and curling use similarly meticulous layering. But for each sport, the ideal ice temperature and thickness is different. Ice skating, for example, touts the thickest and warmest ice: The roughly two-inch surface is held around a balmy 25 degrees Fahrenheit, which allows skaters to hook their skates in the ice as is necessary to perform their gravity-defying jumps and spins.

Some of the magic isn’t just in the engineering—it’s in the nature of ice itself. At its edges, the water molecules in ice aren’t as strongly locked into the honeycomb as in its center, creating a liquid-like layer known as pre-melt that lubricates the surface and is thought to give ice its unique slippery quality. The intense pressure of a skate or blade applied to a tiny sliver of ice can slightly depress its melting point, which likely contributes to that slick layer of water. Slight melting from the friction of a sliding blade on the surface is also thought to add liquid to the mix.

Some Ice Masters try creative measures to achieve the perfect surface. Among ice aficionados, there’s a longstanding myth that music can help ice crystallize. For the 2014 Sochi Olympics, Ice Master Dimitri Grigoriev played classical music—Vivaldi’s “Four Seasons,” to be exact—while laying the icy track. “We had classical playing here, so that the ice crystalizes in the proper hard manner, not rock music, not silence,” he told NPR, adding: “I am serious about it, look it up!” (NPR looked it up, and there is no reputable science to back this claim.)

Seitz isn’t impressed by such superstitions. “If we’re going to do anything we’re probably blasting heavy metal music,” he says—for the crew, not the ice. It keeps his crew “awake and going hard” during the grueling hours of work laying the track, he says.

Read the full story at Smithsonian.com

EnvironmentMaya Wei-Haas