Updated: 01/19/2009 5:10 PM KSTP.com | Print Story
By: Rob Koch

KOCH: Squeaky snow

Have you ever noticed the squeak or maybe you might refer to it as a creak sound you can make walking on snow?  You likely have heard it, but if you need a reminder click here http://www.youtube.com/watch?v=Fezkb36rmEg  It doesn't happen everytime you go and walk on the snow.  For example today,no sqeak walking across the snow.  But last week, it happened just about everyday.  And some days the sound seemed even louder than day before.  To get to the bottom of this think back to how cold it was last week.  Highs Tuesday, Wednesday and Thursday were below-zero.   According to the folks at Cooperative Institute for Meteorological Satellite Studies at the University of Wisconsin, temperature and the pressure of your shoe walking on it creates the snow squeak. 

When the temperature of the snow is 14 degrees or higher, walking does not produce much of any sound.  Colder than 14 degrees, the squeak happens.  Interesting huh.  There's a little more too the squeak.  At a temperature warmer than 14 degrees, the pressure your shoe puts on the snow partially melts the snow allowing it to pass under your boot and no sound is made.   Drop the temperature below 14 degrees, the pressure from your shoe does not melt the snow, instead the ice crystals beneath your boot are crushed.  And that crushing sound it was makes the squeak, or creak sound. 

A very similar process takes place when you go ice skating.  The skate puts pressure on the ice causing a thin layer to melt below the blade permitting it to slide across the layer of frozen water.