Lightning and related phenomena in isolated thunderstorms and squallline systems

During the past few years, cooperative research on storm electricity has yielded the following results of both basic and applied interest from isolated severe storms and squall line systems: 1) the intracloud to cloud-toground flashing ratio can be as great as 40:1; 2) as storm cells in a squall line dissipate, flashes of longer horizontal extent become predominant; 3) two vertically separated centers of lightning activity exist: one at a height of about 5 km and another at about 12 km; 4) storms can produce lightning in their upper regions at a high rate; 5) positive cloud-to-ground flashes occur in the severe stage of isolated storms and in trailing precipitation during the later, well-developed stage of squall line storms; 6) mesoscale convective complexes have been observed to have cloud-to-ground flashing rates of >48 min1; and 7) the electric field in anvils several tens of kilometers away from the main storm core can be very high (> 94 kV-m).