The Science Behind Why You Can Make Snow—Even When It's Above Freezing


Snow is one of the environment's greatest magic tricks, but when Mother Nature's not quite meeting demands, the folks at Hafjell ski resort in Lillehammer, Norway, take matters into their own hands.

While visiting the ski village for the 2016 Youth Winter Olympic Games, YouTuber Tom Scott tackled the science of making snow. The ski resort features about 250 snow guns that pump out the powdery stuff in the form of a well-planned blizzard, keeping the slopes in skiable condition.

The most interesting thing about the snow machines? They work even when the temperature is above freezing. Water and air are forced through nozzles to create a fine mist, and that mist becomes powder instead of rain due to evaporation. When a water droplet evaporates, it pulls in heat from the surrounding environment and cools droplets around it. That process creates nucleation sites and the beginning of snowflake production. If that’s not enough, proteins can also be added to aid the process.

The drier the air, the more water that can evaporate into it, which means that if it’s dry enough, you can actually make snow even if the temperature is above freezing. The converse is also true—high humidity means the temperature needs to be very low, which, as Scott says, is why you’ll never be able to operate a snow gun in the summer.

Hafjell takes its water—a sum of about 30,000 liters (8000 gallons) a minute during a normal season—from lakes at the top of the mountain. See how they recreate the magic in the video above.

[h/t Gizmodo]

Images via YouTube.