On the Scale of Particle Clustering Induced by Inhomogeneous Entrainment-Mixing in Mixed-Phase Cumulus Clouds

In mixed-phase cumulus clouds, droplets and ice crystals are inhomogeneously distributed, such spatial inhomogeneity can be enhanced by inhomogeneous entrainment as it can strengthen the particle clustering, which may further influence the phase partitioning and interactions among hydrometeors. However, the scale of particle clustering induced by inhomogeneous entrainment is not well known. Utilizing high-resolution in-situ aircraft measurements in mixed-phase cumulus clouds, this study shows due to inhomogeneous entrainment-mixing, the cluster scales of droplets and ice crystals decrease by approximately 10 m from the cloud center to the edge. Changes in the clustering are correlated with the intensity of entrainment-mixing. Clouds that are significantly affected by entrainment exhibit stronger enhancement of particle clustering and a more noticeable reduction in cluster scale. The findings from this study improve our understanding of the scale of particle clustering induced by entrainment-mixing, and are potentially helpful in evaluating models.