Abstract
Experimental results of the measurement of vapour pressure of amorphous H2O(H2Oas), ice Ic and ice Ih are described. The vapour pressure of H2Oas is one or two orders of magnitude larger than those of ice Ic and ice Ih and depends greatly on the condensation temperature, Tc and the rate of condensation, R. When Tc is low and when R is small, the difference in vapour pressure between H2Oas and ice Ic is large. On the other hand, with increasing Tc and R the vapour pressure of H2Oas approaches that of ice Ic. Also the vapour pressure of ice Ic is slightly larger than that of ice Ih. We discuss the condensation and evaporation of H2Oas in space.
