The Olympics Has 100 Percent Fake SnowHere’s The Science of How It Gets Made – Scientific American

The following essay is reprinted with permission from The Conversation, an online publication covering the latest research.

The winter Olympics conjure up images of snowy mountain ranges, frozen ice rinks and athletes in cold-weather gear. And for good reason. Winter Olympic venues have often been in places that receive anaverage snowfall of 300 inches per yearor more.

However, barring some extremely anomalous weather patterns, the mountains surrounding the snow events for the Beijing Winter Olympics will be tones of brown and green and nearly devoid of snow. The region typically receives onlya few inches of snowfallin each winter month. This means that basically all of the snow the athletes will be competing on will be human-made.

I am anatmospheric scientistwho specializes in mountain weather and snow. I am also the founder of a snowmaking startup and an avid skier. There are distinct differences between natural and artificial snow, and it will be interesting to see if these differences have any effect on competition.

Snowmaking guns spray tiny droplets of cooled water into the air.

Though artificial snow and natural snow are both frozen water, most skiers and snowboarders are able to immediately recognize that the two are very different.

Traditional snowmaking useshigh pressure water, compressed air and specialized nozzlesto blow tiny liquid droplets into the air that then freeze as they fall to the ground. But snowmaking is not as simple as just making sure the air is sufficiently cold.

Pure water does not freeze until it is cooled to nearly -40 F (-40 C). It is only the presence of microscopic suspended particles in water thatallow it to freeze at the familiar 32 F (0 C). These particles, known as ice nuclei, act as a sort of scaffolding to help ice crystals form.

Without these particles, water struggles to turn into ice. Different particles can raise or lower freezing temperatures depending on their specific molecular configuration.

Two of the best ice nuclei aresilver iodideand a protein produced by the bacteriaPseudomonas syringae. Most snowmaking systems add acommercial form of the bacterial proteinto water to ensure most of the tiny droplets freeze before they hit the ground.

Natural snow starts as a tiny ice crystal on an ice nucleus in a cloud. As the crystal falls through the air, itslowly grows into the classic six-sided snowflake.

By comparison, human-made snow freezes quickly from a single droplet of water. The resulting snow consists of billions of tiny spherical balls of ice. It may resemble natural snow to the naked eye on a ski run, but the natural and artificial snow feel very different.

Due to the fact that the tiny ice balls pack together quite denselyand that some of them may have not frozen until they touched the groundartificial snow often feels hard and icy. Fresh natural powder snow, on the other hand, provides skiers and snowboarders an almost weightless feeling as they soar down the mountainside. This is largely because the natural snow crystals stack very looselya fresh layer of powder is as much as95% or more air.

While fresh powder is what most recreational skiers dream of, Olympic skiers have different tastes. Racers want to be able to glide as fast as possible and use their sharp edges to make powerful, tight turns. The dense, icy conditions of artificial snow are actually better in these regards. In fact, race organizers oftenadd liquid water to race courses of natural snowwhich will freeze and ensure a durable, consistent surface for racers.

Another consideration is the fact that natural snowstorms produce dull, flat lighting and low visibilityhard conditions to race or jump in. Heavy natural snowfall will often cancel ski races, ashappened during the snowy 1998 Nagano Games. For racers, clear skies and artificial snow provide the advantage there, too.

But hard human-made snow does have its downsides. Freestyle skiers and snowboarders who are flying off jumps or sliding on rails high above the ground seem toprefer the softer surface of natural snowfor safety reasons. This is also true of Nordic skiers, who recently flagged thedangers of artificial snow in the event of crashesas icy, hard surfaces can lead to more injuries.

While Olympic athletes have mixed needs for their snow, for the vast majority of recreational skiers, natural snow is far better. Due to the air-filled crystals, it is much softer and more enjoyable to ski or snowboard on.

Scientists have been trying for decades to create more natural snow on demand. The first way that people tried to make real snow was by seeding natural clouds with silver iodide. The goal was to facilitate moisture in clouds turning into falling snow crystals. If you could make this processcalled theWegener-Bergeron-Findeisenprocessoccur more easily, it would theoretically increase the snowfall rate.

In practice, it has historically been difficult to prove the efficacy of seeding. However, recent work using large, meticulously deployed sets of atmospheric instruments has shown thatfor a fraction of storms with the proper conditionsseeding clouds with silver iodide does indeed yield modestincreases in the total amount of snowfall.

Another optionwhich doesnt require storm clouds to seed in the first placeis to create snowmaking machines that can grow fluffy natural snow crystals. Scientists have been growing snowflakes in laboratories for many decades, but the process is delicate, and typically researchers onlyproduce a few flakes at a time. Because ice crystals typically grow slowly, it has been tricky for researchers to scale the process up by the many orders of magnitude needed to grow enough snow for skiing. But in a quest to produce fluffy powder for skiers and snowboarders, my colleague Trey Alvey and I developed a process that can produce snowflakes in larger quantities using a technique that mimics the natural crystal formation process. Were commercializing it through our company calledQuantum Snow.

The dry, barren mountains hosting the 2022 Winter Olympic venues are not exactly a skiing destination. But thanks to snowmaking science, the athletes will have reliable, if icy, runs to compete on. And sports fans can all be thankful for the technology that allows them to enjoy the high-speed spectacle put on by the brave souls who compete in the skiing and snowboarding events.

This article was originally published on The Conversation. Read the original article.

See more here:

The Olympics Has 100 Percent Fake SnowHere's The Science of How It Gets Made - Scientific American