the right of the first dial Semicircles (A, B, C, D, E), representing stabilized nuclear cloud radii for preselected yield groups
(2, 5, 30, 100, and 300 KT), are centered with the azimuth dials around ground zero. An additional semicircle (F) for a 1
MT yield group is provided for the 1:250,000 kilometer scale. A nomograph (fig. 2) is located on the right side of the area
predictor. The nomograph consists of three logarithmic scales indicating effective windspeed in kilometers per hour, yield
of detonation in kilotons (KT), and downwind distance in kilometers. The effective windspeed is normally obtained from
the effective downwind message, and the yield can be estimated by using the cloud parameters, flash-to-bang time, and
the M4A1 nuclear yield calculator. From these two points on the nomograph, the downwind distances for two predicted
fallout zones can be determined. The area predictor is packaged in a plastic case with a copy of this manual.