® 1106 @ Photography on the aase motion cameras showed pronounced pre-shock dust on Engebi, about four miles distance from sero. This is a reascusble thermal effect; despite the initially zero height of burst, the redius of the fireball was in the onfer of 1 mile at this time; it probably hed alrendy risen ; a to sufficient height to provide an appreciable angle of incidence for therml radiation on the ground. A beta densitometer trace from Kirinion shows enormous dust~-losading of the shock wave, but no prre-shock dust-loading., By itself, the shock wave density would be about 1.40 tines normal air density at this pressure level; this record shows that the density reached a maximm of 8.0 tines norm) eeveral seconés after shock arrival. It suggests even worse dust-loading than usually cbeerved om atom bombs, perhaps due to the failure of gravity to seale in such long duration blast waves. Canbeiige Research Center reports fast rise tines in free air. This is egsin consistent with the theory of surface effects, which predicted that | : 4 the rise times should be fast in the absence of s surface perturbation. sation Pertinent menguremente were made by LASL in 6.40 - “Water Waves, Shallow” 6.7Ta - “Underwater Pressures, Seep", and Sandia Corporation in Project 6.7b - Yon and Scrippe Institute Project 6.4 ~ “Sen Waven"; by Bureau of Ebips, Project . J t tn Llald b Lite - ae ne 3 | “Underwater Pressures on Reef", Bo quantitative results are yet available. Predictions for wive heights are contained in J-9543 by George White, "Scaling Yor Surface Explosiona in Sbalicw Water", (1AS1). | Bakery of LASL reports a perceptible wave in the order of a foot near Parry, and & few feet nesy Ronit. These resulte are in reasonable agreement with the predictions by White. Due to damage to the camera no record wes cbtained on me’ BEST AVAILABLE COPY 8. SNI 4 i