Influence of the ice growth rate on the incorporation of gaseous HCl

[摘要] Ice crystals were grown in the laboratory at −15°C, at different growthrates and in the presence of a partial pressure of HCl of 1.63×10^-3 Pa, to test whether the ice growth rate influences the amount of HCl takenup, X_HCl, as predicted by the ice growth mechanism of Domine and Thibert(1996). The plot of HCl concentration inice as a function of growth rate has the aspect predicted by that mechanism:X_HCl decreases with increasing growth rate, from a value that dependson thermodynamic equilibrium to a value that depends only on kineticfactors. The height of the growth steps of the ice crystals is determined tobe about 150 nm from these experiments. We discuss that the application ofthese laboratory experiments to cloud ice crystals and to snow metamorphismis not quantitatively possible at this stage, because the physical variablesthat determine crystal growth in nature, and in particular the step height,are not known. Qualitative applications are attempted for HCl and HNO₃incorporation in cloud ice and snowpack crystals.

[学科分类] 大气科学