Abstract:In recent years, the interaction between aerosols and thunderstorm electrification has emerged as a focal point in academic research. Homogeneous nucleation of soluble aerosol droplets and heterogeneous nucleation of ice nuclei are two primary sources for ice crystal formation. The size and concentration of ice crystals in thunderstorms significantly influence charge generation and distribution, and are critical factors in lightning events. This paper employs a three-dimensional thunderstorm model to investigate the impact of three distinct ice nucleation schemes on lightning discharge characteristics, focusing on a mountain weak thunderstorm case. The results demonstrate that homogeneous nucleation generates a substantial number of ice crystals in the low-temperature zones at the cloud top, resulting in prolonged discharge duration within the thunderstorm. The charge structure is predominantly dipolar, with a lower lightning frequency, primarily consisting of cloud flashes originating from higher altitudes. In contrast, heterogeneous nucleation forms ice crystals in high-temperature zones, leading to an earlier charging process in thunderstorms. Ice crystals in these zones readily meet charge reversal conditions, significantly increasing the negative non-inductive charging rate and favoring the formation of tripolar charge structures. Under these conditions, lightning occurs earlier and initiates from relatively lower altitudes, with heterogeneous nucleation facilitating lightning occurrence. When both homogeneous and heterogeneous nucleation processes occur simultaneously, the thunderstorm charging process intensifies, resulting in a high lightning frequency. Furthermore, both nucleation processes advance the initial lightning occurrence time and expand the height range of the initial lightning trigger points. The tripolar charge structure promotes the occurrence of a substantial number of negative cloud-to-ground flashes.