Variation of Ice Microphysical Properties With Temperature and Humidity at Tops of Convective Clouds

Abstract

The sizes and shapes of ice crystals in cold clouds influence the clouds' evolution and radiative properties (Russotto et al., 2016;Jensen, Harrington, & Morrison, 2018;. In turn, the variation of ice crystal sizes and shapes within clouds are determined by a complex interaction between ice microphysics and dynamic and thermodynamic properties of the atmosphere (Bailey & Hallett, 2004). A better understanding of the many interacting processes governing the formation of complex mixtures of ice of various shapes and sizes in natural ice clouds is required to improve the representation of ice clouds in global circulation models modeling current and future climates (Gasparini et al., 2021;Waliser et al., 2009;Zelinka et al., 2020). In recent work using satellite retrievals over thick ice clouds globally (van Diedenhoven et al., 2020, VD2020 hereafter), we found that systematic variations of ice size and shape with cloud top temperature show a remarkable agreement with simplified ice crystal vapor growth theory and in situ and laboratory data. This agreement suggests that the temperature dependence of the cloud top ice sizes and shapes could be dominated by the vapor growth process and that ice particle distributions observed at cloud top have generally been subjected to depositional growth for a uniform amount of time at average conditions similar to the observed cloud top, which is somewhat surprising given the many processes involved and the large variation in dynamical variables.

Ice Crystal Characterization in Cirrus Clouds III: Retrieval of Ice Crystal Shape and Roughness from Observations of Halo Displays

“…These studies mainly focus on optically thick cirrus. More recently, polarized reflectance observations of the airborne Research Scanning Polarimeter (RSP) have been used to retrieve ice crystal aspect ratio and distortion levels for tops of optically thick ice clouds: van Diedenhoven et al (2012van Diedenhoven et al ( , 2020; van Diedenhoven (2021) found that crystal distortion and aspect ratio increase with cloud top height, leading to decreasing asymmetry parameters.…”

Numerical Modeling of Ice Crystal Dendritic Growth with Humidity by Using an Anisotropic Phase Field Model

“…Diedenhoven et al found that the relative humidity has an effect on determining the temperature dependence of cloud-top ice size and shape. 20 Heymsfield et al 21 found that the macroscopic structures formed by water icing differed under different relative humidity conditions. Li et al 22 investigated the characteristics of icing on the surface of wind turbine blades by varying the relative humidity by spraying water droplets of different diameters and water mists of different flow rates, and calculated and analyzed the icing rate and icing area.…”

“…In recent years, scholars have studied humidity and ice crystal growth. Diedenhoven et al found that the relative humidity has an effect on determining the temperature dependence of cloud-top ice size and shape . Heymsfield et al found that the macroscopic structures formed by water icing differed under different relative humidity conditions.…”

Toward Better Constrained Scattering Models for Natural Ice Crystals in the Visible Region

“…(2017) found that by using models that have both surface roughness and air inclusions, the simulated polarized reflectance is most consistent with remote sensing observations. In recent years, remote sensing approaches have been applied to retrieve the physical properties of ice crystals quantitatively, such as surface roughness, distortion parameter, and overall morphology (Hioki et al., 2016; Saito et al., 2017; van Diedenhoven, 2018, 2021). The validity of remote sensing retrieval is nevertheless dependent on the underlying assumptions about cloud geometry and the prior light scattering models.…”