Brain Post: How Snow Guns Work

Tanner Blake | | BrainsBrains
Fan guns put out a ton of snow
There’s some interesting science that goes into making snow – PC: Tanner Blake

The idea behind snowmaking is simple; you spray water into cold air and it freezes into snow as it falls to the ground. But there’s more to it than that. Engineers have spent nearly 70 years developing snow machines, and as a result, modern snowmaking is really good. Let’s take a look at what goes into it.

Wet bulb temperature chart shows how humidity affects snowmaking
This handy chart shows how humidity and air temperature correlate to give us wet-bulb temperature – PC: Snowathome

These five things are key to effective snowmaking:

  • Water – the main ingredient for snow.
  • Compressed air – to both atomize the water and project it outward.
  • Nucleators – small ice crystals or additives that initiate the freezing process. Without nucleators, the water could potentially supercool without freezing. They give the ice something to form around.
  • Fall distance – the more time that the water spends in the air, the longer it has to cool and freeze.
  • A low wet bulb temperature – this type of temperature reading incorporates humidity and ambient air temperature to tell how cold the water droplets will get while in the air evaporating. Dry cold weather is optimal.
The image shows the difference in snow production between snow lances and fan guns
Notice how the lance-style snow guns let snowdrop, whereas the fan gun produces a higher volume of snow and spreads it further – PC: Tanner Blake

Snowmaking starts with water from a stream or reservoir. The water is then pumped to the snow guns where the fun stuff happens. The first thing needed is some sort of nucleator, something for ice crystals to form on. The nucleator is combined with atomized water and compressed air, and this mixture is blown outward and begins to fall. On the way down, cold ambient air and evaporation cause the water droplets to cool and freeze into ice crystals. The snow that results isn’t quite powder, typically more dense than natural snow, but skiable regardless.

There are a few different ways to build snow guns in order to accommodate the needs of different resorts. Two of the most common styles of snow guns are lance style and fan gun. They both use the same fundamental principles but in different ways. As a result, the two types are optimal for different applications.

Lance snowguns are a simple solution to make snow
These lance-style snow guns are way simpler than fan guns – PC: Tanner Blake

Lance-style snow guns, or “snow lances”, are the ones that make snow from the top of long metal sticks. They use height to provide airtime for the water to freeze. The compressed air that these guns use is supplied from a large central air compressor and is piped out to each individual gun. They usually only have a few nozzles for the snow to come out of, limiting their snow output, but their simple design makes them relatively low maintenance. The snow from snow lances isn’t blown very far from the gun, making them more ideal for narrow runs. These guns also cost much less than their fan-style counterparts.

Fan snowguns have on board air compressors
Fan guns are best for covering wide runs because of the distance that they shoot snow – PC: Tanner Blake

Fan style snow guns are the bulky looking ones that sit low to the ground. These are high-output powerhouses. They have numerous nozzles around the rim that emit lots of misted water into the wind of the fan. Their fans are pretty powerful, and they blast snow high into the air and across a run. The extended airtime and extra wind from these fans allow these guns to produce snow that is better frozen, and higher quality, than the snow from a snow lance. They also need electricity to power onboard air compressors and their fans. Overall, these guns are better for wide runs and less optimal weather. The downside of all this technology is that there’s a lot more that can break, and that they cost about five times more than snow lances.

Image shows how many nozzles are on a fan gun - it's a lot
Look at all those nozzles! A lot of water can come out of these things, and that means a lot of snow – PC: Tanner Blake

Engineers have also found a few tricks that help them make snow more effectively. One trick is to cool the water before it enters the snow gun, making droplets more likely to freeze in the air. Snowmakers have also tried all sorts of different nucleators. They have used things like small ice crystals and minerals, but one of the more interesting additives is a type of dead bacteria that produces a type of nucleation-active protein. Finally, snowmakers have found that it helps to leave the recently made snow in a pile for a few hours before grooming it. This technique, called curing, allows snowflakes to freeze thoroughly before being disturbed and can improve the quality of the snow.

Short snowguns don't work as well as others
These shorter snow guns do the job, but due to their low spray height they aren’t as effective as snow lances or fan guns – PC: Tanner Blake

So next time you’re skiing on man-made snow, take a second to appreciate the complexities that went into producing it. It took a lot of people a lot of thinking and experimenting to get us to where we are today.


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2 thoughts on “Brain Post: How Snow Guns Work

  1. I thought that CO2 was also used as an additive to the water/air stream, possibly to make the snow fluffier. Can you comment ?

    1. I don’t think that CO2 is used in modern snowmaking. Liquid CO2 can be used to make colder, higher quality snow, but I haven’t read anything about resorts applying the technology. It seems to be more experimental than practical.

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