The fall speeds of sub-100 micron ice crystals

TL;DR

This paper presents new estimates for the fall speeds of sub-100 micron ice crystals, revealing potential overestimations in current models and offering a theoretical approach applicable to non-spherical aerosols.

Contribution

It introduces a novel calculation method for ice crystal sedimentation rates based on new capacitance data, improving accuracy for small particles.

Findings

Good agreement with laboratory data

Current models overestimate fall speeds by up to a factor of two

Method applicable to non-spherical aerosol particles

Abstract

Estimates for the sedimentation rate of realistic ice crystals at sizes smaller than 100 $\mu$m are presented. These calculations, which exploit new results for the capacitance of ice crystals, are compared with laboratory studies and found to be in good agreement. The results highlight a weakness in contemporary ice particle fall speed parameterisations for very small crystals, which can lead to sedimentation rates being overestimated by a factor of two. The theoretical approach applied here may also be useful for calculating the sedimentation rate and mobility of non-spherical aerosol particles.