The Science Behind Snowmaking: How ski resorts keep up every winter

Weather Blog
Featured image taken from I AM a Snowmaker – Bristol Mountain video clip linked below.

ROCHESTER, N.Y. (WROC) — When Mother Nature is lacking, we sometimes use a little help from the art of snowmaking. As mentioned in the clip below, the process works sort of like an iceberg; 90% of it isn’t visible at first glance. It requires the pumping of air and water uphill using up to thousands of gallons of water at a time. A snow gun is then used to blow the air and water into tiny water droplets high up in the sky, and as they freeze they fall to the ground. Voilà, you have snow! 

Without the help of snowmaking, many resorts would not be able to function at all.

There are two types of snow guns:

The first type uses both compressed air and water. It has enough force that it splits the water stream into tiny droplets. The compressed air also allows these water droplets to be launched high in the sky to allow them enough time to freeze and fall as snow. This type is less expensive, but it requires two different inputs.

The second type only requires one input; water. It merely uses an electric fan to blow a stream of water into the tiny water droplets, and is called an airless snow gun. The “pro” to this method is that you don’t need a hose for the compressed air, but you do need an electrical connection to run the fan.

Checking in with Mother Nature

Having the right atmospheric conditions is critical for snow making. Important variables to keep in mind include:

  • Air Temperature
  • Wet Bulb Temperature
  • Relative Humidity
  • Wind Speed/Direction
  • Altitude

As noted in the top few points above, the most important variables to keep track of is the air temperature, wet bulb temperature, and humidity. The wet bulb temperature is essentially the temperature that a wet thermometer will cool to when cold air is blown over it. At the right conditions, this replicates the requirements needed for water droplets to freeze and form snow; similar to what water droplets are exposed to during snowmaking. Humidity plays a key part in determining the wet bulb temperature as it takes into account how much moisture content there is in the air, and is an important part of snow making.

Ideally, you want a wet bulb temperature to be below freezing or colder, but you can still make snow if temperatures are above freezing as long as the air is very dry. It takes a combination of both cold and dry enough air to get just the right snow making conditions.

How it works:

Water drops are able to freeze more quickly when the air is dry due to the evaporation process. The effect in play is known as evaporational cooling. Too much moisture in the air can prevent air from cooling effectively, which is why a lower humidity is ideal for the cooling process.

To sum things up, it works like this: At 100% relative humidity the air temperature and the wet bulb temperature are about the same. When the humidity goes down, the wet bulb temperature also decreases, and having a wet bulb temperature in the teens is the most ideal for snow making.

The best climate for snow making is found away from oceans, such as the Midwest mountainous regions of the U.S. However, we can create our own snow making conditions here in the Northeast. All we need is surge of cold air in the form of a cold front, and an area of high pressure bringing in dry and quiet weather on the other side.

Knowing what the winds are doing is also crucial to good snow making, because you want to aim your snow gun with the wind so you can get your snow to land where you want. Having enough altitude and angle with your snow gun can also increase the amount of time the water droplets have suspended in the air to freeze, which makes for the most efficient snow making.

MORE|What makes a snowmaker?

“To assure our skiers and snowboarders of the best possible snow conditions, Bristol Mountain is proud of its state-of-the-art snowmaking system which covers 100% of the terrain.”

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