Causes and Factors of Ground-Ice Formation

The concept of ground ice is expanded to cover all forms of ice formed at the interface between two environments—the solid state and the gaseous. Ground ice is thus defined as the product of the layer-by-layer freezing of liquid water or droplets of any origin as it passes from a zone of positive temperatures into a zone below the freezing point. Ground ice may be produced by subsurface waters (springs and groundwater), surface waters (river, lake, sea, glacier and snow meltwater) and atmospheric moisture (glaze, rime, hail). The definition excludes ice formed within the solid-state environment of the lithosphere (segregated ice, cement ice, injection ice).] Ground ice produced by subsurface waters may be formed at the surface or in large subterranean cavities, and it may be associated with the natural discharge of water or with the freezing of aquifers. Ground ice produced by surface waters may be associated with an increase of water volume in a waterbody as the level of the ice cover remains stable; with a constriction of the discharge cross section, and with changes in heat and moisture exchange. Ground ice derived from atmospheric moisture is formed either on terrestrial objects (glaze, rime) or in the free atmosphere (hail, ice formed on aircraft).