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Show 9 Interpretation. A community of deposited snow crystals gains its bulk strength from cohesion among the individual particles. As soon as the crystal branches touch one another without further disturbance, the sintering process begins to establish bonds at the contact points. Mass transfer, principally by vapor diffusion, deposits ice to bridge the contacts and welds them together. ( Hobbs and Mason, 1964) Bulk mechanical strength of the snow layer will be determined by the number of these bonds as well as the structure of the original crystals* if the crystals are rime- free, there is an opportunity to form a single sintered bond at each contact between arms of adjacent crystals. In the case of stellar or dendritic crystals, mechanical interlocking is also possible, contributing : to the felt- like structure, of low- density new snow. Given the same crystals forming the same matrix, but rime particles coating each with a. pebbled surface, each contact between arms fi'hds more than dhe possible jubcture or near^ tyneture between rime particles and thus the opportunity for multiple sintering bonds. If these bonds are favored at certain relative crystal 1ographic orientations of the two contacting ice particles, then the multiple contacts of rimed particles will offer augmented probability for the encounter of favored orientat ions. As the degree of riming increases, the branched crystals become filled and mechanical interlocking is no longer possible. Instead of a readily deformed felt- like structure, the snow takes on the character of a coarse- grained aggregate which culminates in the stiff, dense graupel layer. Although viscosity measurements related to different |