Olympic skiers and snowboarders in China compete on 100% fake snow – the science of how it’s done and how it affects performance

The Winter Olympics create images of snow-capped mountains, frozen skating rinks and athletes in gear for cold weather. And for good reason. Winter Olympic venues were often in the receiving venues the average snowfall is 300 inches per year or more.

However, except for some extremely abnormal weather conditions, the mountains around the snowy events at the Beijing Winter Olympics will be brownish-green and almost snowless. The region usually only gets a few inches of snow every winter month. This means that almost all the snow on which athletes will compete will be created by man.

I am atmospheric scientist specializing in mountain weather and snow. I am also the founder of a snow startup and an avid skier. There are clear differences between natural and artificial snow, and it will be interesting to see if these differences affect competition.

Snow cannons spray small drops of chilled water into the air.

How to make fake snow

Although artificial and natural snow is frozen water, most skiers and snowboarders can immediately recognize that they are very different.

Traditional use of snow high pressure water, compressed air and specialized nozzles blow into the air tiny droplets of liquid, which then freeze, sinking to the ground. But making snow is not as easy as just making sure the air is cold enough.

Pure water does not freeze until it has cooled to almost -40 F (-40 C). It’s just the presence of microscopic suspended particles in the water let it freeze at acquaintances 32 F (0 C). These particles, known as ice cores, act as a kind of scaffolding that helps form ice crystals.

Without these particles the water will struggle to turn to ice. Different particles can raise or lower the freezing temperature depending on their specific molecular configuration.

Two of the best ice cores silver iodide and a protein produced by bacteria Pseudomonas syringae. Most snowmaking systems add a commercial form of bacterial protein water so that most of the tiny drops freeze before they hit the ground.

Glide on man-made snow

Natural snow begins as a tiny crystal of ice on an ice core in a cloud. When the crystal falls through the air, it is slowly grows into a classic hexagonal snowflake.

For comparison, artificial snow freezes quickly from a single drop of water. The resulting snow consists of billions of tiny globular balls of ice. On the ski slope, it may resemble natural snow to the naked eye, but natural and artificial snow “feel” very different.

Due to the fact that the tiny ice balls get together quite tightly – and that some of them may not have frozen until they touch the ground – artificial snow often feels hard and icy. Fresh natural “powdery” snow, on the other hand, provides skiers and snowboarders with an almost weightless feeling when they hover down a mountain slope. This is largely because natural snow crystals form very loosely – a fresh layer of powder is just as much 95% or more air.

While fresh powder is what most amateur 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, steep turns. Dense, icy artificial snow conditions are actually better in this regard. In fact race organizers are frequent add liquid water to the racetrack from natural snow which will freeze and provide a durable, uniform surface for riders.

Another view is the fact that natural snowstorms create dim, even lighting and low visibility – difficult conditions for a race or jump. Heavy natural snowfall often cancels ski races, as took place during the 1998 Snow Games in Nagano. For riders there is also an advantage – clear skies and artificial snow.

But solid artificial snow has its downsides. Freestyle skiers and snowboarders who jump off springboards or glide on rails high above the ground seem to prefer a softer surface of natural snow for security reasons. This also applies to Scandinavian skiers who have recently noted danger of artificial snow in case of accidents because icy, hard surfaces can lead to more injuries.

Imitating nature

While Olympic athletes have mixed snow needs, for the vast majority of amateur skiers natural snow is much better. Thanks to the crystals filled with air, skiing or snowboarding is much softer and more enjoyable.

Scientists have been trying for decades to create more natural snow on demand. The first way people tried to make “real” snow was by sowing natural clouds with silver iodide. The goal was to turn the moisture in the clouds into falling snow crystals. If you could do that process – head Wegener-Bergeron-Findeisen process – easier to happen, theoretically it will increase the rate of snowfall.

In practice, it has historically been difficult to prove the effectiveness of sowing. However, recent work using large, carefully deployed sets of atmospheric instruments has shown that – for the proportion of storms under the right conditions – seeding clouds with silver iodide does indeed yield modest the total number of snowfalls increases.

Another option – which primarily does not require storm clouds – is to create snow machines that can grow fluffy natural snow crystals. Scientists have been growing snowflakes in labs for decades, but the process is delicate, and usually only researchers produce several flakes at a time. Because ice crystals usually grow slowly, it was difficult for researchers to increase the process by many orders of magnitude needed to grow enough snow for skiing. But in an effort to produce fluffy powder for skiers and snowboarders, my colleague Trey Ellie and I have developed a process that allows you to produce snowflakes in larger quantities using a technique that mimics the natural process of crystal formation. We commercialize this through our company called Quantum snow.

The dry, barren mountains where the 2022 Winter Olympics are held are not a place to ski. But thanks to the science of snow, athletes will have reliable, albeit icy, runs for competitions. And sports fans can be grateful for the technology that allows them to enjoy a high-speed spectacle, which is arranged by brave souls who participate in skiing and snowboarding competitions.

Written by Peter Wills, Professor of Atmospheric Sciences, University of Utah.

This article was first published in Conversation.