How Snowmaking Works

By: Kyler Roush

Up until a week ago, the snowpack across almost any trail at almost any resort could almost entirely be contributed to snowmaking. Fortunately those days appear to be behind us (knock on wood). Most of us skied by the snow guns without even thinking much more than “I hope my goggles don’t freeze over!” After weeks of that turned into a couple months, my thoughts began to change to, “How does all this really work?”

Snow enthusiasts Art Hunt, Dave Richey, and Wayne Pierce invented and patented the first snow gun in 1950. Two years later, in 1952, Grossinger’s Catskill Resort and Hotel adopted snowmaking as a way to bypass Mother Nature. By 1970, snowmaking had become a widespread industry across the nation.

We were all taught in kindergarten that water freezes at 32 degrees. However, water can remain liquid all the way down to -40 degrees under the right circumstances. Water can also remain a liquid below 32 degrees depending on the humidity in the air, but can also freeze above 32 degrees depending on the humidity.

Now that some of you are confused, let’s talk about how NATURAL SNOW is formed.

In science class we were taught about the water loop: Evaporation, Condensation, and Precipitation.

As water evaporates off the surface of bodies of water, it rises into the air. For every 1000 feet that water vapor rises into the atmosphere, the temperature drops about 3.5 degrees. Eventually the vapor will cool enough and condense into water droplets which fall back to earth. In the mountains we like it when the water vapor changes directly from vapor into a solid. That is how we get snow crystals. When the crystals begin to combine they turn into snowflakes, which then fall upon our beloved mountains.

So what about that -40 degree water?

In order to freeze, water needs something to act as a point of nucleation. Sometimes the point of nucleation is that magical rope barrier that keeps us safe in the resorts. When that happens, we get Rime Ice.

Now on to the snow machines…

There are 2 main types of snow guns. The first is the air/water guns. In an air/water gun there are two hoses that run to the gun, one containing compressed air and the other containing water. The water is sprayed out of nozzles that “atomize” the water into very fine droplets. The compressed air is included at this point. When the compressed air expands it cools dramatically to -40 degrees, our magic number where water MUST freeze. Now we have very small frozen droplets. These now act as our points of nucleation for a second set of water nozzles. These newly atomized droplets can now freeze as snow crystals onto the previously frozen droplets. These crystals now finish their journey by falling into piles of snow for the snow cats to move around.

The second type of snow gun works off a similar concept. These are called fan guns. Similar to the air/water guns, fan guns have 2 sets of nozzles. The first set creates very small frozen droplets and the second set adds more droplets that can then crystallize on the points of nucleation. The fans replace the need for compressed air by blowing the atomized droplets out into the air where they fall to the ground. Without the release of compressed air the temperatures remain well above -40, but this is where natural particulates in the air help out by providing a point of nucleation for the first nozzles to freeze on.

Now we all know the conditions that go in to snow making, but there is more to know other than making piles around the mountain. In the beginning of the season, snow makers tend to put out a very heavy and dense snow to create a base to cover hazards. After a base layer has been put down, they will begin to make a lighter, less dense snow to create a better ski surface.

Other info:

-On average it takes 200,000 gallons of water to cover 1 acre in 1 foot of snow. This number varies based on the temperature and humidity.

-As of mid-January, Deer Valley in Utah had pumped 255 million gallons of water through their snow guns. On an average year, Deer Valley will only use 175 million gallons in total

-During a similar time frame, Snowbird had used approximately 80 million gallons.