Accession Number : ADP001804

Title :   Criteria for Onset of Firestorms,

Corporate Author : TRW SPACE AND TECHNOLOGY GROUP REDONDO BEACH CA

Personal Author(s) : Carrier,G. F. ; Fendell,F. E. ; Feldman,P. S.

Report Date : 1981

Pagination or Media Count : 6

Abstract : Quantitative criteria are evolved for onset of firestorms, severe stationary (nonpropagating) holocausts arising via merger of fires from multiple simultaneous ignitions in a heavily fuel-laden urban environment. Within an hour, surface-level radial inflow from all directions sustains a large-diameter convective column that eventually reaches altitude of about 10 km (e.g., Hamburg, Dresden, Hiroshima). As the firestorm achieves peak intensity (2-3 hours after the ignitions), inflow speeds are inferred to attain 25-50 m/s; typically 12 km2 are reduced to ashes, before winds relax to ambient levels in six-to-nine hours. Here the firestorm is interpreted to be a mesocyclone (rotating severe local storm). Even with exceedingly large heat release sustained over a concentrated area, in the presence of a very nearly autoconvectively unstable atmospheric stratification, onset of vigorous swirling on the scale of two hours requires more than concentration of circulation associated with the rotation of the earth; rather, a preexisting, if weak, circulation appears necessary for firestorm cyclogenesis. (Author)

Descriptors :   *Nuclear explosion damage, *Explosion effects, *Fire storms, Ignition, Flame propagation, Combustion, Atmospheric motion, Cyclones, Intensity, Peak values, Environments, Estimates, Urban areas, Symposia

Distribution Statement : APPROVED FOR PUBLIC RELEASE