Crystal growth in the presence of surface melting: supersaturation dependence of the growth of columnar ice crystals

Abstract

We report measurements of the growth rates of the basal (0 0 0 1) and prism (101̄0) facets of ice as a function of surface supersaturation, in a regime where the growth dynamics are dominated by the presence of surface melting. Our measurements were made using freely falling columnar ice crystals, growing a solvent gas of air at a pressure of one atmosphere, with ambient supersaturation levels 1<σ_∞<11%. Condensation coefficients for the two facets were inferred by modeling the effects of both particle and heat diffusion, which also yielded surface supersaturation levels 0.75<σ_(surf)<2.2%. Our results show a strong supersaturation dependence in the crystal growth, as for both facets the condensation coefficient exhibited a precipitous drop below σ_(surf)≈1%. In addition, the condensation coefficient for the basal facet was found to be nearly a factor of 10 larger than for the prism facet. These results support a model in which the ice growth rates are governed by 2D nucleation at the interface between the crystalline solid and a quasi-liquid surface layer.