Derivation of Thunderstorm Ice Hydrometeor Characteristics from Lightning Measurements

Previous calculations (Blyth et al., 2001) predicting that the lightning frequency f is proportional to the product of the downflux p of solid precipitation (graupel) and the mass upflux I of ice crystals, have been subjected to preliminary examination by analyzing data from the STERAO experiment. The analysis has yielded provisional support for this flux hypothesis. The physical reasons for such a relationship are explained in terms of the paramount role of ice in the electrification of thunderstorms. These calculations have been extended in order to derive direct relationships between f and p. The expression for f/p depends upon the glaciation mechanism. If primary nucleation is dominant f is roughly proportional to the first power of p, but if Hallett-Mossop nucleation prevails the exponent is about 1.5. The estimated values of precipitation yield per lightning flash, Y, are 10 and 2.10 kg/flash respectively. These predictions are in reasonable agreement with field data.