How the atmosphere works for those curious about weather and the world

Tuesday, February 7, 2012

Impact Is More Important Than How Much Snow Falls

Here in Cincinnati we are just far enough north to get disruptive snow events almost every winter and just far enough south that sometimes we are dealing with the icy stuff.

By icy stuff I mean the precipitation that is transitional between snow and rain.  Because of the geometry of storm systems in the middle latitudes the cold air at the surface is sometimes overrun by warmer air.  When snow falls through the warm layer it can melt into rain and then when it hits the colder-than-freezing surface splat and freeze into a glaze of ice. Glaze is the agreed upon international name for waht we call freezing rain.

If the cold air at the surface is deep and well below freezing the snowflakes that melted to raindrops can refreeze into small ice pellets, which is the internationally agreed upon name for them. We call it sleet.

Everyone knows the helpless feeling of hitting a patch of friction-free glaze ice on foot or worse in a car and that is almost always worse than several inches of snow.

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