Evaluation of the Effect of Electro-Coalescence and Anti-Electro-Coalescence with Conducting Sphere Approximation on the Formation of Warm Cumulus Cloud and Stratocumulus Cloud

The Conducting Sphere (CS) method is an advanced analytical approach for studying electrostatic force treatment, surpassing the image charge method by accurately reproducing multi-dipole charged droplets. This method enhances understanding of electro-coalescence and anti-electro- coalescence phenomena in cloud simulations. To investigate the impact of electro-coalescence and anti-electro-coalescence in cloud, the CS method is implemented to the super-droplet method.

We performed two weak electric charge simulations using CS methods: a cumulus simulation to evaluate electro-coalescence effects on droplets with opposite charges, and a stratocumulus simulation to assess anti-electro-coalescence effects on droplets with the same charge. Opposite charge CS treatment significantly enhanced precipitation, even at 3% charge levels. Total domain precipitation increased by 52.5% compared to no charge settings and surpassed the image charge treatment by 5.36%. When the charge ratio exceeded 100, short-range attractive electric forces from multi-image dipoles substantially enhanced cumulus cloud precipitation. The simulation of stratocumulus clouds with same charges demonstrated an enhancement in cloud cover and cloud radiative properties when compared to the scenario with no charges. It is found that the charged droplets could affect cloud formation even when the droplet charge is lower charge limit. Despite a slight increase in simulation time (30%), the accurate outcomes justify implementing the conducting sphere method.

This presentation showcases the significant improvement in calculating electrostatic forces between droplets within warm cumulus clouds and stratocumulus clouds, achieved through the utilization of the conducting sphere method. Additionally, it explores how these electrostatic forces contribute to cloud formation processes.