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Fig. 7. Crystals of "spring" or corn snow. the humidity is such that no net evaporation results, since the difference in vapor pressure will cause ice to evaporate from the points and attach itself to flatter portions of the crystals. The result is a gradual transformation from branched or thin-edged snow crystals to larger hexagonal crystals. The smaller crystals in turn tend to consolidate with larger crystals. By this basic process new-fallen snow is converted gradually to the "spring snow," which every skier knows (fig. 7). The rate and manner of change will depend on the weather, but the process is always going on, and accounts for variations in the internal cohesion of the snow. Cohesion is at first reduced by the loss of the interlocking crystal branches, but as the process continues, the large crystals which are finally formed pack more closely, so that the snow settles and cohesion again increases. But when temperature and humidity produce wet crystals, the film of water, acting as a lubricant, reduces internal cohesion. |
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