Field identification of a unique globally dominant mechanism of thunderstorm electrification

Abstract

ABSTRACT:Two wholly distinct studies involving TRMM-satellite global data were conducted. One involved the relationship between lightning frequency f and brightness temperature, the other between f and ice-water-path. Both studies demonstrate that globally valid relationships exist between f and thundercloud ice-precipitation content, from which it follows that graupel pellets play a crucial role in thundercloud charging. Ground-based field studies provide further support for this conclusion and show that f is also strongly dependent upon the ice crystal content. All these findings are consistent with the non-inductive charging mechanism, but not with any other proposed mechanism of thunderstorm electrification. We conclude that the non-inductive mechanism dominates electric field growth and lightning production in all seasons-for both oceanic and terrestrial thunderstorms-on a global scale.

On the relationships between lightning frequency and thundercloud parameters of regional precipitation systems

“…Scatter diagrams of lightning flash rate versus parameters of minimum 85 GHz PCT, minimum 37 GHz PCT, maximum radar reflectivity near −15°C and area of 35 dBZ echo near −15°C are combined in Figure 6. Linear regression equations for the scatter diagrams in Figure 6 are listed as follows (Y is flash rate, while X is the value of different parameters): The IWM at 8 km is closely correlated (R = 0.80-0.94) with lightning frequency as expected from the literature Deierling et al, 2005;Latham et al, 2007]. Of all the TRMM-observed parameters, 35 dBZ area at −15°C has the best positive relationships (R = 0.78-0.94) with (Figure 6).…”

“…[3] Relationships between thundercloud parameters and lightning are based upon the generally accepted noninductive charging (NIC) hypothesis [Latham et al, 2007]. In NIC, it is hypothesized that particle-scale charge separation occurs through rebounding collisions between precipitationsized ice particles and abundant small ice crystals in the presence of supercooled liquid water [Takahashi, 1978;Saunders et al, 1991;Saunders, 1993;MacGorman and Rust, 1998].…”

Effect of bacterial ice nuclei on the frequency and intensity of lightning activity inferred by the BRAMS model

“…Petersen et al (2005) found a linear relationship between total lightning flash rate and ice water path, independent of the regime (land, ocean or coastal zones). Likewise, based on the charging zone concept, several studies have shown strong correlation between the total (intra-cloud and cloudto-ground lightning) flash rate and the precipitable and nonprecipitable ice masses (Blyth et al, 2001;Latham et al, 2004Latham et al, , 2007Deierling et al, 2008). The terms precipitable and non-precipitable ice masses are associated with the hydrometeor types likely to precipitate or not, relative to the convective core updraft, i.e., denser particles like hail and graupel can precipitate over the convective core and are defined as precipitable ice mass, while snowflakes and ice crystals cannot and are therefore defined as non-precipitable ice mass.…”

“…Latham et al (2004Latham et al ( , 2007 have extended the relationship on Eq. (2) to several studies in the literature, and restate the correlation between F , f P and f NP .…”

“…During the rebounding collisions, electric potential charge is transferred between the particles with opposite signs. Concerning the non-inductive mechanism as the main process responsible for cloud electrification, there are many observational or modelling studies such as Reynolds et al (1957); Williams and Lhermitte (1983); Dye et al (1989); Rutledge et al (1992); Latham et al (2007), among others. The amount of charge transferred depends on the particle sizes and their fall velocity, while the sign depends on the cloud temperature and supercooled liquid water content (e.g., Takahashi, 1978;Saunders et al, 1991Saunders et al, , 2006Pereyra et al, 2000;Takahashi and Miyawaki, 2002).…”