ABSTRACT
Snow and ice are significant elements of the world hydrological system, which occur subject to tremendous variations in space and time. Snow or ice are present in the atmosphere, in lakes and rivers and oceans, on the land, and even beneath the earth’s surface. Ice is characterized by crystals of the hexagonal system, and commonly takes on a variety of prismatic, pyramidal, or dipyramidal forms. Hexagonal symmetry occurs, and is especially prominent in the aggregates of ice crystals which form snowflakes. Snow and ice which occur at the earth’s surface may be schematically viewed as a simple input-output subsystem within the hydrological cycle; that is, the growth or diminution of ice and snow cover is a response to net differences between accumulation (water input) and ablation (water output). Agriculture, transportation, and flood control are only a few of the activities which are influenced by the size and duration of the snow cover.
