B/Ltr_ fr Hqs, WREP, APO a Francisco, Calif., Subj: Balloons, dtd 13 Mar 54 Weather Other balloons received are admittedly of the poorer types available. The operators making the observetions have done extremely well with the materiel at their_disposal, 4. The secondary reason for failure to obtain the desired heights is the very low temperature encountered at the tropopause in this region which is much lower than in the United States. In general the balloons become hard and brittle losing their ability to expand or to retain their internal pressure as they rise and thus burst at a comparativcly low altitude. 5. The third reason for failure: to obtain the desired heights is moisture incountered, especially at Majuro, Kusaie and Ponape. Perhaps the ice crystals formed weaken the balloon, but this is a technical matter which I am not qualified or prepared to evaluate. The results aro consistont. When excessive moisture is present, camparativaly low heights arc obtained and no amount of re-releases will produce increased heights. 6, If new balloons are procured, the most expeditious supply action would require two and a half wecks to place them in the hands of the gperating personnel. Thus 375 of cach type would be necessary to complete the operation if Rongerik can be returned to operation by the end of this-mcntl or 300 of each type necessary if Rongerik is not returned to full cfe®tton but used only one or two days prior to shot days. 8. Faétors to be considered im making the decision on ordering addit- -Lonel balloons are as follows: a. New balloons may attain average heights of 10,000 feet greater than present balloons, foet and above. Many individual heights may be expected to 100,000 This may or may not be at critical times. b. New balloons would probably not be received prior to 27 March. c. Additional expense will be required to obtain the balloons, The 500 gram night balloons will cost $900.00 if Rongerik is not returned to full operation and $1050.00 if Rongerik is in full operation during April I understand that some $5000.00 originally set aside by Task Group 7.4 for the purchase of the original 500 gram balloon was not used, if so, this monoy should be available for that purpose. The other balloon is a standard Air Force item and should entail no additional expense, Other costs would be for transportation and handling which I have no means of cstimating. d. The highest possibleheights arc desircd by.wonther forecasters and radiological safcty people. It has been learned that serious fall-out may occur from heights above those attained by rawinsonde observations at present, Definite information at higher levels than presently obtainable may prove to be of vital importance in radiological safety considerations to be made affecting the final order for firing each shot. Peculiar winds at these higher levels may indicate serious fall-out over such populated locations as Eniwetok or Kwajalein which would not be suspected without this information. a f eet

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