Aerosol‐Cloud Interactions and Their Role in Modulating Lightning Activity: Evidence From Extreme Events Over India

Abstract Lightning activity across the Indian subcontinent has exhibited a sharp rise in recent years, with significant implications for public safety, especially under a warming climate. This study examines the role of aerosol‐cloud interactions in modulating lightning flash rates using the Weather Research and Forecasting (WRF) model for two intense premonsoon lightning events over distinct climatological regions in India: west‐central India (16 April 2019) and Northeast India (6 May 2013). Simulations were conducted using three aerosol‐aware microphysics schemes, Morrison, National Severe Storms Laboratory (NSSL), and Fast Spectral Bin Microphysics (FSBM), in combination with various boundary layer and cumulus schemes. The FSBM–Yonsei University–Grell‐3D configuration yielded the best agreement with observations, minimizing errors in temperature, planetary boundary layer height, and lightning flash rate. Sensitivity experiments revealed a nonlinear relationship between cloud condensation nuclei (CCN) concentrations and lightning activity: flash rate increased with aerosol loading up to an optimal CCN value (∼7,500 cm −3 in west‐central India and ∼3,000 cm −3 in Northeast India) beyond which lightning activity declined. A similar threshold behavior was observed with aerosol size, where coarse‐mode particles enhanced lightning rates, but giant aerosols (≥30 μm) led to suppression. These effects were linked to changes in updraft intensity, water vapor content, and graupel formation, key factors influencing charge separation. The results show the importance of region‐specific meteorological conditions in governing the response of lightning to aerosol perturbations and highlight the need to incorporate such nonlinearities into predictive frameworks.