The science behind making snow

Snow guns.

Most anyone who has ever gone skiing or snowboarding has seen them endlessly blasting away on the sides of a trail, coating ski slopes in man-made snow.

And while many seasoned riders can talk your ear off about how man-made snow is heavier, wetter and lacking in that indescribable “pow” quotient that natural snow has, you’d be hard pressed to find a skier or snowboarder who doesn’t see the value the man-made white stuff provides.

snowmaking snow gun
The image on the left is a close-up of natural snow. The one on the right is man-made. So it turns out there is merit to the notion that natural snow is better. Photo: Courtesy of NASA

But does anyone really understand how snowmaking works? How is it snow guns are able to blow snow when the weather doesn’t otherwise permit the formation of those beautiful frozen water crystals? Is it wizardry?

RELATED: Tahoe resort using revolutionary method to blow snow all summer

To answer these questions we called Robin Smith, the general manager for TechnoAlpin — the world’s largest snowmaking company. Here’s what he had to say:

snowmaking snow gun
There’s a whole bunch of science behind freezing water and shooting it into the air. Photo: Courtesy of John Lemieux/Flickr

So, explaining it to somebody with an almost nonexistent grasp on science, how is snow made?

There’s two basic systems of making snow.

In the industry, one of the methods is called “air-water.” Those are basically the snow guns you see mounted on the side of trails that look like 50 caliber machine guns.

In that system, small frozen droplets of water are shot out into the atmosphere using highly pressurized water and air, and as they’re leaving the gun the droplets become “snow flakes” by attaching to particles of dirt in the atmosphere — those particles are known as seed nuclei.

RELATED: Lake Tahoe resort recycling wastewater snowmaking

In the other system, which uses fans to spread the snow, the snow flakes are made by a compressor inside each machine.

In those, the frozen particles are attached to the seed nuclei — which are only about 20 microns wide — in the snowmaker and then distributed by a large fan.

Generally speaking, the fan systems distribute the snow the furthest and are better for wide trails while the air water guns are better for narrow trails.

snowmaking snow gun
Fan systems are better for covering wide swaths of ski slopes in the white stuff. Photo: Courtesy of Sugarloaf

So then how is it that snow guns can operate in temperatures above freezing?

Well, the reality is that traditional snowmaking machines can’t operate above freezing, it just seems that way to you because of the temperature you are reading. Snow guns can only operate if it’s 28 degrees Fahrenheit wet-bulb or lower.

Traditionally, people read a thermometer, and maybe it will say it’s 30 degrees Fahrenheit outside. That’s well and good, but that reading doesn’t take into account humidity. A wet-bulb reading is a more accurate reading as it measures 100 percent relative humidity in the area.

So in other words, your car thermometer might say its 40 degrees, but if you’re in a place like Colorado, where the air is very dry and the atmosphere isn’t already saturated with water, the wet-bulb temperature might be 14 or 16 degrees, so it appears they’re making snow above freezing.

But on the East Coast, where there’s a lot amount of humidity in the air, the wet-bulb temperature will look more akin to the traditional thermostat you’re reading.

snowmaking snow gun
The Snow Factory (above) is capable of producing snow at temperatures above 60 degrees. Photo: Courtesy of TechnoAlpin

So one of the reasons we called you is because of your Snow Factory system. We wrote about how it’s a new system that allowed Boreal Mountain Resort up in Lake Tahoe to blow snow through July. How does that work?

So snowmaking, I believe, began in the 1950s when a farmer invented a spray rig in an attempt to freeze proof his apple orchard, but instead of water what came out was more like snow. And there haven’t been a whole bunch of advances in it since then.

What we do with the Snow Factory is much simpler than that: We basically construct the biggest ice making machine you’ve ever seen, like what would be behind a bar, but the size of a shipping container.

But instead of cubed ice we make flaked ice, in pieces thinner then a dime, and where an ice cube simply needs to be frozen, ours are frozen to an extremely low temperature, which makes them more resistant to thawing.

And surprisingly, when a cat goes over our stuff it’s much different than normal man-made snow. It skis much better.

Originally we thought that 60-65 degrees Fahrenheit would be the highest reaches of what we could produce our snow at, but Boreal was making it up to 90 degrees. A lot of it was melting, but our snow allowed them to keep one rail park run open through July.

snowmaking snow gun
While the thought of being able to blow snow year-round might sound tempting to snow deprived resorts, the chances of that are slim. Photo: Courtesy of Kris Arnold/Flickr

So does that mean that, with this new technology, we can expect to see more resorts staying open year-round?

Unfortunately, that’s not too likely.

One Snow Factory on its own won’t produce enough snow to maintain an entire ski run, at least not well enough. It has about the same production as one of the fan systems running at marginal temperatures, but a Snow Factory’s energy consumption is four times that of a normal snow gun.

So to attempt to keep an entire resort open year round using only Snow Factories would be really inefficient.

However, if you were to strategically implement Snow Factories in ski resorts that already have traditional snow guns and the temperatures for conventional snowmaking, you could prolong a ski season pretty far.

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