Vapor pressure above ice at temperatures below 170 K

[1] Ice clouds in the earth's atmosphere and the presence of ices in comets and on planetary surfaces have raised the interest in the formation and existence of ice particles and of ice in bulk matter. Of special importance are the saturated vapor pressures well below 200 K. Marti and Mauersberger [1993] published a simple, experimentally derived equation that covers the temperature range from 273 to 170 K. Measurements have been extended toward 165 K and they show a clear departure in saturated vapor pressures when compared to a single-fit Clausius-Clapeyron expression over the entire temperature range. The equation derived for temperatures below169 K, log P = -3059/T + 14.88 (P in Pa and T in K), is significant for extrapolations of ice vapor pressures to temperatures in the mesosphere where clouds form well below 160 K.