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Fig. 6. Typical forms of new snow crystals. crystals are formed when the temperature is low. The range of size is, roughly, from 1-4 mm. in diameter. A snowflake frequently consists of a cluster of interlaced snow crystals. Snow crystals of the simple plate form accumulate loosely compared to the branched type of crystal. The points of the branched crystals interlace and cohere within a mass of new-fallen snow. An avalanche is, therefore, less likely to occur immediately after a snow- fall made up of branched crystals. Snow made up of the simpler type of crystals will flow more readily. Consolidation of crystals.—As soon as snow has fallen a transformation begins. If the temperature is above freezing, the branches of the crystals begin to melt, destroying the interlocking bond. Even if the temperature is below freezing, these branches will still, although more slowly, disappear because the vapor pressure of the ice particles, and consequently evaporation, is greatest at the points. This evaporation will take place even though |
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