Accession Number : AD0661827

Title :   EXPERIMENTAL STUDY OF TRIGGERED NATURAL LIGHTNING DISCHARGES.

Descriptive Note : Final rept.,

Corporate Author : LIGHTNING AND TRANSIENTS RESEARCH INST MINNEAPOLIS MINN

Personal Author(s) : Newman,M. M. ; Stahmann,J. R. ; Robb,J. D.

Report Date : MAR 1967

Pagination or Media Count : 62

Abstract : Studies of the natural lightning discharge channel have been continued in the Summer of 1966 using a triggering technique during which 17 strokes were triggered out of 23 attempts. The discharges were triggered by firing a rocket carrying a fine wire to an altitude of about 400 meters when electric field meters indicated a discharge was probable. The studies showed clearly in the Fastax photographs, the current oscillograms, and in the still photographs the existence of a low current continuing component lasting up to 0.8 seconds following nearly every initial high current stroke. Also, high current restrikes were found after nearly every stroke with as many as a dozen restrikes in a single lightning discharge. Blast pressure measurements showed higher peak pressures than measured previously from triggered natural lightning discharges and also longer durations. This is of interest in relation to possible structural damage to aircraft and also in relation to shock wave effects on flame propagation in aircraft fuel vents. High speed motion pictures of the discharge clearly showed the violent snake like motion of the channel of importance in evaluation of stroke sweeping effects near aircraft. (Author)

Descriptors :   (*HAZARDS, AIRCRAFT), (*AVIATION SAFETY, LIGHTNING), (*LIGHTNING, SCIENTIFIC RESEARCH), (*FLORIDA, THUNDERSTORMS), SOUNDING ROCKETS, METEOROLOGICAL PHENOMENA, ATMOSPHERIC SOUNDING, STABILITY, CLOUDS, PHOTOGRAPHS

Subject Categories : Atmospheric Physics
      Meteorology

Distribution Statement : APPROVED FOR PUBLIC RELEASE