抄録
Condensation, metamorphism and evaporation of water ice and mixtures containing CO, CO_2 and CH_4 are thought to be important for the evolution of cometary ice. Based on recent laboratory studies, an overview is given on the physical properties of amorphous ice and on condensation, metamorphism and evaporation of various ices. It is shown that the macroscopic defect structures in amorphous ice play an important role not only in the retention of other volatile molecules but also in the thermal properties. Discussions of the influence of the physical properties of amorphous ices on the origin and thermal evolution of comets are presented. The formation conditions for amorphous ice by vapor deposition are also discussed.
