“…They do generally agree that relatively warm, moist environments support positive graupel electrification, so that will be the focus of discussion in this manuscript, with the acknowledgement that the precise temperature and moisture characteristics that result in either positive or negative graupel electrification are debated (e.g., Saunders & Peck, 1998; Takahashi, 1978). There are many additional factors that can also influence electrification: Particle roughness can affect the relative growth rate of hydrometeors and by extension the polarity of charge transferred in collisions (e.g., Avila et al., 2005; Glassmeier et al., 2018; Tsenova & Mitzeva, 2009); impact velocity may also be a factor, as included in rime accretion rate‐controlled laboratory studies (e.g., Brooks et al., 1997; Saunders & Peck, 1998); and electrification at low water content is under active investigation (e.g., Dye & Bansemer, 2019; Luque et al., 2016).…”