Optical Properties

Pure ice is transparent, but air bubbles render it somewhat opaque. The absorption coefficient, or rate at which incident radiation decreases with depth, is about 0.1 cm-1 for snow and only 0.001 cm-1 or less for clear ice. Ice is weakly birefringent, or doubly refracting, which means that light is transmitted at different speeds in different crystallographic directions. Thin sections of snow or ice therefore can be conveniently studied under polarized light in much the same way that rocks are studied. The ice crystal strongly absorbs light in the red wavelengths, and thus the scattered light seen emerging from glacier crevasses and unweathered ice faces appears as blue or green.

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