-3Research has been conducted in the special field of tropical meteorology, and weather observers and forecasters have been instructed in the new methods of forecasting which have been developed as a result of these studies. Trained personnel have been organized into a fallout prediction unit. They will utilize newly-—developed fallout computers, will assist in precicting fallout patterns by mechanizing most of the mathematical procedures involved. Use of the computers is expected to allow fore- casts to be made much more rapidly than heretofore, so that the final decision to conduct or postpone a test can take last-minute weather observations into account.+ Models: of the clouds produced by large-scale nuclear detonations have been developed as a result of experience gained from the 1954 testing operations, and these also are expected to improve fallout predictions. 1The fallout computer, designed by the National Bureau of Standards, works in the following way: Weather information and estimates of the diameter and height of the cloud and the distribution of radioactivity within the cloud are fed into the computer by setting various dials. One-twentieth second after the data is set up, the machine visually displays a predicted fallout pattern on the face of a television-—like tube. The predicted radioactive intensity at any point up to 250 miles or more from ground zero is indicated by the brightness of the pattern at the particular point in question.