As temperatures begin to drop across ski country, resorts are preparing their snowmaking systems for another winter. While cold air is obviously essential, there is more to making machine-made snow than simply waiting for the thermometer to fall below freezing. According to Snow State, there are several key ingredients that must come together before a ski resort can effectively make snow.
Wet Bulb Temperature Is Key
The most important measurement for snowmaking is the wet bulb temperature, which accounts for both air temperature and relative humidity. Snowmaking generally requires a wet bulb temperature below 28°F.
This means snowmaking can theoretically occur even when the actual air temperature is above 32°F if humidity is low enough. Evaporation removes heat from water droplets as they travel through the air, helping them cool and freeze before reaching the ground. Humidity therefore plays a major role. Lower relative humidity creates more evaporative cooling and can allow snowmaking to operate at higher air temperatures.
Most snowmaking systems perform best when wet bulb temperatures are in the lower 20s or colder. Warmer conditions can produce wetter, heavier snow, while wet bulb temperatures in the teens can allow machines to produce much drier and powderier snow.
The Snowmaking Ingredients
Cold conditions are only one part of the process. Snow guns also require compressed air and pressurized water. Compressed air helps cool the water and plays an important role in nucleation, the process that allows tiny water droplets to begin freezing. Pressurized water is forced through specialized nozzles that create droplets of an appropriate size for freezing.
The snow gun combines these ingredients and sprays the resulting droplets into the atmosphere. If conditions are cold enough, the droplets freeze before reaching the ground and accumulate as machine-made snow.
Why Some Snowmaking Nights Are Better Than Others
Even when temperatures are technically cold enough, the quality and quantity of snow produced can vary significantly. Water volume, temperature, humidity and the type of snow gun being used all affect the final product. That’s why ski resorts closely monitor weather conditions before firing up their snowmaking systems.