9626542 Marshall While much has been learned over the last decade concerning the electrification of thunderstorms, quite a bit is still unknown. There are several competing theories concerning the mechanism by which charge centers develop, but research is still ongoing to determine which of these are valid and under what conditions. Under this award the Principal Investigator will pursue two research objectives: (1) investigate how electric charge inside thunderstorms evolves during the life of the storm; and (2) investigate whether most of this charge is carried on precipitation-sized particles. To accomplish these objectives, the Principal Investigator will participate, in conjunction with other researchers, in two observational efforts one in New Mexico and one in Oklahoma. Beneath thunderstorms, the Principal Investigator will launch balloon-borne instruments that will measure the electric field bulk charge and the charge on individual precipitation particles. To meet objective (1), a series of balloons will be launched about ten minutes apart into each storm to be studied. The locations of the main charges in the storm can be inferred from the electric field measurements made with each balloon launch and with other supporting instrumentation from aircraft. To meet objective (2), the findings from the precipitation particle charge instrument will be compared to the bulk charge inferred from the electric field measurements. Both of these experiments will provide information on how thunderstorms acquire large amounts of electric charge. By providing information about the evolution and distribution of charge in thunderstorms, this research will advance the current understanding of how these dangerous and damaging thunderstorms become electrically charged. ***
