Snow, Ice, Avalanches, and Glaciers - Mountain Geography: Physical and Human Dimensions - page 158

FIGURE 4.8 (A) Kinetic metamorphism diagram showing the crystal change over time in the presence
of moderate temperature gradients. When temperature gradients are extremely large, crystals
can progress directly from stellars at the left to more advanced faceted crystals shown on the
right. (Image courtesy of L. R. Dexter and K. Birkeland.) (B) A scanning electron microscope im-
age of a sample faceted crystal. (Image courtesy of E. Erbe.)
THE INTERNATIONAL CLASSIFICATION FOR SEASONAL SNOW ON THE GROUND
A comprehensive snow classification system exists for all types of seasonal snow (in-
cluding new snow, described previously): the International Classification for Seasonal
Snow on the Ground (ICSSG) (Fierz et al. 2009). The ICSSG is fairly involved but, at
the coarsest level, it consists of nine fundamental snow and ice types, based mainly on
grain shape:
1. Precipitation particles (identical to the eight ICSI classes)
2. Machine-made snow (typically made for skiing)
3. Decomposing and fragmented precipitation particles (including windblown new
snow)
4. Rounded grains (equilibrium metamorphism)
5. Faceted crystals (kinetic metamorphism)
6. Depth hoar crystals (advanced kinetic metamorphism)
7. Surface hoar (deposition of kinetic forms onto the snow surface)
8. Melt forms (melt-freeze metamorphism)
9. Ice formations (horizontal ice layers and vertical ice columns from piping)
This system is the standard used by most workers in snow-related endeavors around
the world.