What causes a Winter Snow Storm?
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> By Rachelle Oblack , Weather Expert
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> Moisture is the first ingredient necessary to produce a
> winter storm. Moisture is water in air.
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> Moisture in air comes from evaporation from lakes, riivers,
> seas, trees leaves.
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> Although it may seem like common sense, temperatures must be
> below freezing not only in the clouds but also at
> the ground surface.
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> Believe it or not, it can and does snow in the desert, but
> it never reaches the ground because of the high
> temperatures!
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> When warm air meets with cold air warm air rises over
> the cold air.
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> The boundary between the warm and cold air masses is called
> a front.
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> Snowstorms happen when a mass of the warm air rises quickly
> and the cold air cuts underneath it.
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> This leads to heavy snowfall.
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> see attached picture of meeting two fronts.
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> Also note that Warm air is lighter than the cold air.
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> Therefore the warm air will always be over the cold
> air.