Estimating Surface Attachment Kinetic and Growth Transition Influences on Vapor-Grown Ice Crystals

Abstract

There are few measurements of the vapor growth of small ice crystals at temperatures below -30°C. Presented here are mass-growth measurements of heterogeneously and homogeneously frozen ice particles grown within an electrodynamic levitation diffusion chamber at temperatures between -44 and -30°C and supersaturations ( si) between 3 and 29%. These growth data are analyzed with two methods devised to estimate the deposition coefficient ( α) without the direct use of si. Measurements of si are typically uncertain, which has called past estimates of α into question. We find that the deposition coefficient ranges from 0.002 to unity and is scattered with temperature, as shown in prior measurements. The data collectively also show a relationship between α and si, with α rising (falling) with increasing si for homogeneously (heterogeneously) frozen ice. Analysis of the normalized mass growth rates reveals that heterogeneously-frozen crystals grow near the maximum rate at low si, but show increasingly inhibited (low α) growth at high si. Additionally, 7 of the 17 homogeneously frozen crystals cannot be modeled with faceted growth theory or constant α. These cases require the growth mode to transition from efficient to inefficient in time, leading to a large decline in α. Such transitions may be, in part, responsible for the inconsistency in prior measurements of α.

Re-evaluating cloud chamber constraints on depositional ice growth in cirrus clouds – Part 1: Model description and sensitivity tests

“…Recent experimental work suggests that depositional ice growth rates (Bailey and Hallett, 2002;Harrison et al, 2016;Pokrifka et al, 2020;Harrington and Pokrifka, 2021) and surface complexity (Schnaiter et al, 2016;Voigtländer et al, 2018) may be impacted by whether heterogeneous or homogeneous nucleation initiates the ice growth process. Prior to nucleation, experiments on heterogeneous ice nuclei have demonstrated surface defects on mineral dust serve as active sites for growth (Kiselev et al, 2016).…”

“…Homogeneous nucleation instead is dependent on a phase transition leading to crystallization in supercooled aqueous droplets, which occurs spontaneously without requiring preferential nucleation sites. result of heterogeneous nucleation has been suggested to be dominated by dislocation growth (Harrison et al, 2016), whereas measurements also suggest that homogeneously nucleated ice is initially dominated by dislocations but may rapidly transition to ledge nucleation growth (Pokrifka et al, 2020).…”

“…Recent progress on modeling surface kinetic processes on faceted single crystalline ice has been made with the development of the Diffusion Surface Kinetics Ice Crystal Evolution (DiSKICE) model, which approximates ice with two semi-axes to model crystal habits, allowing for different ice aspect ratios to be consistently modeled during depositional ice growth (Zhang and Harrington, 2014). The theory can capture the growth of crystals with various aspect ratios using a single, supersaturation and temperature dependent deposition coefficient (Harrington et al, 2019), which may make it amenable to modeling more complex crystal forms (Pokrifka et al, 2020).…”

“…While Skrotzki et al (2013) explored the variability in the deposition coefficient derived from experiments performed at various temperatures and with two types of heterogeneous ice nuclei, the analysis method implicitly assumed that α D remained constant during a single expansion experiment, investigating only the constant parameterization typically used in cloud models. Recent advances in modeling surface kinetic processes on faceted ice in cirrus clouds Harrington, 2014, 2015) and in experimental measurements of individual ice crystals (Pokrifka et al, 2020) provide motivation to reanalyze these experiments. In this paper (Part 1) we describe the adaptation of a parcel model including different models for surface kinetic effects to the AIDA experiments Harrington, 2014, 2015), and compare predicted ice growth rates under varying assumptions for surface kinetic effects.…”

Studies on the Competition Between Homogeneous and Heterogeneous Ice Nucleation in Cirrus Formation

“…Thus, this study showed that the manner of nucleation can affect the subsequent crystalline habit. Levitation diffusion chamber studies also indicate that homogeneously frozen droplets have deposition coefficients that are distinctly different from crystals nucleated heterogeneously (Pokrifka et al., 2020). These studies suggest that some of the crystals formed from homogeneously frozen drops have deposition coefficients that evolve from high to low values during the experiment.…”