The Systematic Observation of the Thundercloud and Lightning

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The systematic thunderstorm observation was caraaid out at Orlando, Florida during the thunderstrom season in 1993. Concerning the Japanese scientist groups, Osaka University is assigned to the electric field change observation at the two different points simultaneously using the newly developed wideband slow antenna. Gifu University is assigned to the observation of a lightning channel by a video camera and by an optical measurement system which maintains the high spatial resolution and we can obtain an idea on the lightning channel variation in the direction of the diameter. Gifu University also equipped an optical measurement system with which they can discriminate the time difference of so called simultaneous multi point lightning strikes. On the other hand concerning the group of U.S., National Severe Storm Laboratory (NSSL) is assigned to taking high speed video pictures of lightning channels by a hand made whole sky camera. New Mexico Tech is assigned to the operation of the VHF imaging system of lightning channel in side the thundercloud.Since the lightning discharge is a transient phenomena which is sometimes shorter than 1 sec., the most laborious work for the multi point observation is the operation of the common and accurate time standard. Normally we use the transient memory to record the observed signals and To produce the common trigger signal is often difficult, We equipped the two slow antenna 2.5 km away each other and we decided that for the trigger signal of the systems The luminous signal emitted from lightnings discharges is used. We are convinced the excellent synchronization of recorded data at two different point without the real time connection.We had eight thunderstorm days in early August and captured many preferable data. Those are surely effective to understand the mechanism of simultaneous multi point lightning strikes. The analysis is undertaken at each Institute.