Snow science: How mountains make snow

Newsroom Meteorology Snow science: How mountains make snow

It’s bound to happen at some point this season. After a long day of skiing six inches of powder at your favorite resort, a friend calls from a nearby resort and brags about their epic powder day. You’re tempted to call them out on it, but could they be telling the truth? Sure they can.

The simple way to put it is mountains manufacture their own snow. No, we’re not talking about snowmaking machines, we’ll get to that in a moment or two.

You know doubt know from personal experience that the higher you go up a mountain, the colder it gets. So when the atmosphere gets thinner and thinner, the air isn’t able to retain heat and dissipates and falls was cold air. When that air reaches 32 degrees Fahrenheit (O Celsius), the water freezes and it will snow. Did you know that all rain starts as snow and then melts while falling?

Natural snowfall
Snow falls naturally when it’s 32 degrees. (Freepik)

So, how do the mountains do their thing?

The moist wind hits a mountain and is forced to rise. Rising air expands due to lower pressure and that expanded air cools, allowing the moisture to condense into the snow. The process (good for apes ski trivia) is called orographic lift. It is responsible for making more than half of the snow that naturally falls on large mountains.

Then, there’s convective precipitation that occurs when air vertically rises through a portion of the atmosphere fed by heating, moisture, and vertical forcing. In other words, the moisture is forced out of the atmosphere as precipitation.

Snowguns b last
Snowguns blast water and pressurized air on to the ski slopes

What about “human-made” snow?

Snowmaking has probably been the single most important factor that has saved our skiing and snowboarding season ever developed. Here’s a fun fact: The first snowmaker, per se, was Louis Gelb, a Warner Brothers technical director, who conjured up a cold and wet blizzard on a sunny day on the studio’s back lot in Burbank, California. This first-ever snowmaking machine consisted of three rotating blades that shaved ice from a 400-pound block and a high-powered fan that blew all those particles into the air. That probably started it all.

We can all use weather models to find snow

Snowmaking today works on the same principle but has become amazingly sophisticated. Water and pressurized air are forced through a snow gun or a large “cannon.” Voila! snow. It is used to assure the reliability of a resort’s snow cover. It can add to the snowpack or actually be the snowpack. And, it is so good, you won’t know the difference between what was shot from guns or what fell from the sky.

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