where: A, A‘ are the gamma exposure rate levels as a function of distance along the fallout hotline for an +1 hour reference time (R/hr) 6, Q' are the directional shears in the fallout hodograph from the surface to the top of the radioactive cloud (degrees) h, h! are the radioactive cloud depths (feet) Vv, v' are the resultant mean transport speeds fram the surface to an appropriate altitudein the radioactive doud (mph) ft, f' are the fallout fractions (%) Y, ¥' are the fission or fission equivalent yields of the nuclear devices (xt ) the exposure rate level (A'), when computed, is applicable at the downwind distance X' = «(2\(2) n/\v (Eq II) | where: xX, xX! are downwind distances along the fallout hotline (statute miles) h, h' and V, V' are defined as in Eq I above. (Note: Eq II is reversed in practice to solve for X rather than X' thereby facilitating computational procedures). The unprimed quantities are obtained for the analog event by an analysis of observed exposure rate levels, meteorological conditions, and radioactive cloud dimensions. All yield information is obtained from the nuclear laboratory executing the detonation. If a reliable method of predicting the fallout fraction f' were available the value of this parameter could be a variable. Estimates of f' for cratering experiments can be made, however,