Toward a Comprehensive Model of Snow Crystal Growth: 6. Ice Attachment Kinetics near -5 C

TL;DR

This paper develops a comprehensive physical model for snow crystal growth at -5°C, incorporating structure-dependent attachment kinetics and diffusion processes to explain diverse observed morphologies.

Contribution

It introduces a unified model that accounts for various snow crystal forms and complex structures through structure-dependent attachment kinetics and diffusion effects.

Findings

Model explains diverse snow crystal morphologies at -5°C

Attachment kinetics depend on local crystal structure

Diffusion processes are integral to crystal growth dynamics

Abstract

I examine a variety of snow crystal growth measurements taken at a temperature of -5 C, as a function of supersaturation, background gas pressure, and crystal morphology. Both plate-like and columnar prismatic forms are observed under different conditions at this temperature, along with a diverse collection of complex dendritic structures. The observations can all be reasonably understood using a single comprehensive physical model for the basal and prism attachment kinetics, together with particle diffusion of water vapor through the surrounding medium and other well-understood physical processes. A critical model feature is structure-dependent attachment kinetics (SDAK), for which the molecular attachment kinetics on a faceted surface depend strongly on the nearby mesoscopic structure of the crystal.