Using Formvar to Capture Ice Crystals and Retrieve Roughness Parameters

Abstract. Ice crystal roughness is a poorly observed and understood parameter, yet it significantly influences crystal’s scattering properties and consequently impacts radiative transfer in the atmosphere, contributing to uncertainties in weather and climate forecasting. In this study, we introduce a novel approach to obtain high-resolution roughness measurements, building on the traditional formvar method for capturing ice crystals. Ice crystals were grown in the Manchester Ice Cloud Chamber, collected, and subsequently imaged using various techniques, including a scanning optical profilometer, which enabled the identification of roughness features as small as 0.8 µm. This approach provides critical insights into roughness characteristics that are significant for improving radiative transfer models and forecasts.