size, of approximately 1,200 yards from weapons of the present tactical Since this al application of iswithinthe range of total blast destruction, the only practic column. afterwinds would be their role in drawing ground debris inte the rising cloud may play a Tt is possible that with extremelylarge weapon yields the afterwinds y, significant part in surface destruction, although this appears to be rather unlikel 3. TROPICAL WEATHER FORECASTING a. This project was a part of a long range program in tropical weather forecasting and was considered to be a part of the GREENHOUSE program only because of the many weather observations which were available during the test period. This — work was under the direction of Dr. C. E. Palmer, University of California at Los Angeles, an eminent authority on tropical forecasting. b, It is too early to determine the results of the study of the meteorolo- pical data which were obtained during Operation GREENHOUSE; however, it can be men— tioned that an improved method of forecasting, stressing streamline analysis, was tested and found to be encouraging. It should be pointed oul that the usual fore- casting techniques employed in temperate latitudes, involving the interpretations of highs and lows in barometric pressure, and fronts and air masses, are entirely inadequate in the tropics due to the very iinor pressure variations and the uniformity of air masses, The field of tropical forecasting ts almost a virgin one and will undoubtedly involve the formulation of many entirely new concepts, A, ATMOSPHERIC CONDUCTIVITY a, of the cloud. The last project of this program wes the study of the ionic structure A total of four aircraft were equipped with suitable equipment for the measurement of conductivity. Two of these were L-13 liaison aircraft, which were equipped with one smali ion conductivity chamber for low altitude crater and local fall-out surveys. The others were long range B-SOA aircraft designed for tracking the cloud up to 3 days after shot time; these were fitted up as flying leboratories. These aircraft were equipped with instruments to measure both positive and negative small jon density and large ion density simultaneously with continuous records of atmospheric nuclei counts, electrostatic field, humidity, speed and samples of the atmosphere, b. prossure, temperature, air | The plan of operations was to intercept the atomic cloud 4 hours after shot time with the B-50As and run contours around the outer edge continuously to obtain size and rate of growth of the cloud, and at the same time deterntine the density of large and small ions on the fringes of the cloud. ~3.. This was done from 4 hours af-