Accession Number : AD0616550

Title :   TRIGGERED LIGHTNING DISCHARGES AND APPLICATION TO V.L.F. PROPAGATION STUDIES.

Descriptive Note : Final rept. pt. 1,

Corporate Author : LIGHTNING AND TRANSIENTS RESEARCH INST MINNEAPOLIS MINN

Personal Author(s) : Newman,M. M.

Report Date : OCT 1964

Pagination or Media Count : 23

Abstract : Natural lightning discharge observations in VLF propagation studies would be greatly helped by direct measurements of the lightning discharge currents corresponding to received wave shapes at various locations. Consequently a technique for triggering, recording and identifying natural lightning discharges has been evolved by rocket-launching a conducting wire into charged thunderstorm clouds, and superposing a 1000 mega-watt peak radiated power 'signature' pulse. Thunderstorm areas of greatest overhead charge intensity were followed by monitoring gradient variations at sea, with an initial frequency of triggering of two discharges brought down out of five rocket firings of 1000 ft wires. Corona current measurements on the wire on the way up indicated negligible disturbance of the cloud charge before the actual lightning stroke was triggered. The triggering wire was vaporized but the consequent lightning discharge current continued to flow along the path of the wire through current measuring shunts which provided accurate oscillographic recording of the lightning discharge current wave shape. Extended use of the technique of triggering natural lightning should permit recording of at least a few ligntning discharges which simultaneously produce whistlers. Coordinated observations at various laboratories should provide further useful data on ionospheric and whistler mode propagation. (Author)

Descriptors :   (*LIGHTNING, MEASUREMENT), (*THUNDERSTORMS, ELECTRIC DISCHARGES), VERY LOW FREQUENCY, PROPAGATION, WHISTLERS, IONOSPHERIC PROPAGATION, ATMOSPHERIC ELECTRICITY

Distribution Statement : APPROVED FOR PUBLIC RELEASE