This award will support Professor Martin Uman of the University of Florida in collaboration with Professor Carlo Mazzetti of the University of Rome and Professor Carlo Nucci of the University of Bologna, Italy. The investigators intend to develop the best possible lightning return-stroke model with which to calculate lightning-induced voltages on power lines; and to test and improve, given the electric and magnetic fields from the return- stroke model, the available power line coupling models in order to arrive at an optimum one. Due to the large diffusion of sensitive solid state electronic devices in control and regulation systems of power and telecom- munications lines, the problem of induced voltages by nearby lightning strokes is of increasing concern. In this work, experimental data on lightning-induced power line voltages and associated electric and magnetic fields from nearby natural lightning and from artificially initiated lightning (via rocket triggering), will form the bulk of the data base. The collabora- tion, which will involve theoretical studies done in cooperation with Swiss researchers, will complement both experimental and theoretical research performed at the University of Florida.