|MadSci Network: Earth Sciences|
Dear Maia, Ice freezes in hexagonal crystals because of the way the water molecules stack together. As in any crystal, the slower the ice crystals grow, the more perfect they can be and the more delicate their appearance. In natural clouds, snow flakes can be built up single molecules at a time. These flakes have been photographed in detail thousands of times and the photos can be found in books and on the internet. Snow machines make snow by blowing high-pressure water thorugh a nozzle which allows it to freeze in an immitation of natural snow. This process produces ice crystals much faster than they are produced in clouds and therefore does not allow the crystals as much time to "grow". The ice crystals are still hexagonal because that is how water freezes, but the delicate lace appearance is not apparent. The "snow" crystals are stubbier without the fancy details you recognize as a typical snow flake. For that reason, man-made snow does not "ski" the same way natural snow does. The fine, deep, dry snow known as "champagne powder" is only made by natural processes in clouds. While man-made snow is not quite as good as the natural kind, it is still better than not being able to ski at all.
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