Monday, December 13, 2010

Pray for (Natural) Snow?

This past Saturday kicked off my instructing duties for the year (two level 1’s).  And Sunday marked the first time that I’ve skied natural snow since October 16th.  Vive la différence.

I have always said that natural snow is better.  It looks better, it skis better, and it melts better (spring corn instead of degraded ice chunks).  I tried to look up some hard statistics to back up my feelings, but all I found were scientific journal entries like this:
A theory is developed to explain the transition from regular plates to dendritic stellar crystals; the corners sprout when material from the vapour phase arrives at corners more rapidly than it can be carried away by surface diffusion and occurs only when the diameter of the plate exceeds a critical value dc, Ds, /Dv, = agrx2p, /Dv, where Ds, Dv, are the coefficients of surface and volume diffusion and xp, is the surface migration distance on the (prism) edge of the plate. The predictions of the theory are compared with observations on natural snow crystals. Equations are derived for the growth rates of snow crystals as they fall through the atmosphere. The predicted maximum attainable diameters of the various shapes are in good agreement with observations
 Which is cool (if you like reading scientific journals), but it doesn’t really explain why natural snow feels so different.  Investigating further, I found this from the Wyoming Climate Atlas:
Mountain ski resorts augment natural snow cover with man made snow, especially during meteorological droughts. 28° F is the "magic number" for snowmaking. When the temperatures drop below this mark, snow production is greatly enhanced. Ten inches of natural snow, when packed, usually adds only one inch of snow to the ski slope’s base while 10 inches of man-made snow adds seven inches of base. Man-made snow is usually more dense and durable
 Okay, so now we’re getting somewhere.  Using a rough estimation, that means that normal Wyoming snow is about 10% water, but man made snow can approach 70% water.  Even if you consider that Eastern Snow has a slightly greater water content than Wyoming Snow (Wikipedia puts it at 15%), that’s still an enormous difference.  Imagine walking through a McDonald’s ball pit where 10% of the space was taken up by balls (and somehow they were floating all around you).  Then imagine a McDonald’s ball pit with 70% of the space taken up by balls.  Movement would be harder, you’d have to use more energy to get through, and the dynamic of how the balls interacted with each other would be completely changed.

That’s the problem with man made snow.  Every single man-made snowflake is heavier, denser, and more watery than its natural counterpart.  And since the number of snowflakes that fall in the world (naturally) is approximately 1,000,000,000,000,000,000,000,000, that means that you are skiing through an awful lot of dense snowflakes.

But, I suppose it’s an early season sacrifice that we all have to live with.  This article on does point out that man-made snow is good for one thing – base buildup:
Harris said man-made snow is more dense and durable. It will hold up better to the abuses of thaws and skis. At the same time, skiers love the natural pow[d]er. Its softer and more fun, Harris said. The idea is to lay down a heavy base of the man-made snow and let the natural snow top it off.

“Then you’ve got the best of both worlds,” Harris said
Can’t argue with that.  Ski areas have to strike the right balance between natural and man-made.  And every mountain is different.  What works for Mad River Glen won’t necessarily work for Hunter.  I guess when it comes to snow, I’d prefer that Gore would heed the words of Saint Augustine:

"Pray as though everything depended on God. Work as though everything depended on you." 


  1. I thought the natural snow was more spikey with lots of little points that made it more airy and foofular. But your explanation sounds good too.

  2. What are these formulas, and theories and science that you speak of? I am just a simple caveman and snow scares and amazes me.

    -Caveman Skier

    /good stuff