Hyperquenched glassy water

There exist different types of ice (see also Fig. 1.12). The ice we know from everyday live (also snow) has a hexagonal structure. At higher temperatures and pressures ice can also form a cubic structure 4). Other forms of ice are called II, III, V, VI, VII, VIII, IX and X. The difference between these forms is their crystalline structure. One also speaks of low-density amorphous ice (LDA), high-density amorphous ice (HDA), very high-density amorphous ice (VHDA) and hyperquenched glassy water (HGW). 

LDA forms by extremely quick cooling of liquid water ( hyperquenched glassy water , HGW), by depositing water vapour on very cold substrates ( amorphous solid water , ASW) or by heating high density forms of ice at ambient pressure ( LDA ). 

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