Ice crystals growing from vapor in supercooled clouds between -2.5° and -22°C: Testing current parameterization methods using laboratory data

Ice crystal growth rates predicted from capacitance theory are compared with measurements from three independent laboratory studies. When the growth is diffusion- limited, the predicted growth rates are consistent with the measured values to within about 20% in 14 of the experiments analyzed, over the temperature range -2.5° to -22°C. Only two experiments showed significant disagreement with theory (growth rate overestimated by about 30%-40% at -3.7° and -10.6°C).

Growth predictions using various ventilation factor parameterizations were also calculated and compared with supercooled wind tunnel data. It was found that neither of the standard parameterizations used for ventilation adequately described both needle and dendrite growth; however, by choosing habit-specific ventilation factors from previous numerical work it was possible to match the experimental data in both regimes.