Interaction and orientation dynamics of charged columnar ice crystals settling in clouds

The interaction and settling of ice crystals and other hydrometeors inside turbulent cloud environment plays a crucial role in modelling the Earth’s radiation budget as well as it gives rise to certain distinctive optical phenomena such as sundogs and light pillars. Understanding the orientation distribution of ice crystals inside clouds also plays a crucial role in accurately designing certain remote-sensing equipment. In this study, we investigate the interaction dynamics of two columnar ice crystal settling under the action of gravity in a background turbulent flow resembling the cloud environment. The ice crystals are considered to be like-charged as can be observed in the upper parts of deep convective as well as mixed-phase clouds. The columnar ice crystals are modelled using the slender body theory, to capture the hydrodynamic interaction between them in a turbulent background flow. The effect of background turbulence is incorporated using a stochastic model which can predict the statistical behaviour of the turbulent velocity gradients. Based on this, we have predicted the probability density function of the orientations of the settling ice crystals. Furthermore, we also study how the electrostatic forces modify the settling trajectories and orientation distribution of the ice crystals. Our results indicates that the electrostatic forces and background turbulence significantly affects the orientation distribution of the columnar ice crystals, providing key insights into the microphysical behaviour of ice crystals inside clouds.