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aircraft kept going farther south to yet another cloud line that developed and appeared suitable. Cloud base <br />height had become higher to the south. <br /> By 00:19 UT had found a new good looking (from the top) cloud as it flew south. Seed 1 and seed 2 had <br />arrived at this cloud area by at 00:28 UT and determined that the cloud base was not formed well enough for a <br />seeding mission and the cloud subsequently was disqualified. The aircraft continued still farther to the south to <br />yet a new line that had a good top looking at 00:32 UT. Again, when the base airplanes arrived at 00:38 UTthey <br />disqualified the cloud for having an unsuitable base. <br /> All aircraft continued farther to the south and arrived at the next cloud line at 00:38 UT where Seed 1 <br />conducted monitoring passes. All monitoring occurred at 14 kft. Seed 3 began seeding under this cloud mass at <br />9 kft at 00:47:15 UT system time and continued seeding for 6:00 minutes continuously. As soon as Seed 1 had a <br />positive identification of the seeded location, it made a pass there and got a large hit of 0.59 volt at 00:53 UT, <br />which is equivalent to about 7000 ppt of the SF gas. Seed 1 made a repeated penetration using the floating <br />6 <br />pointer, but could not get another gas hit. On the third attempt to penetrate the cloud had grown too vigorously <br />with a very high tower occupying the seeded location to the extent that it had to abandoned for flight-safety <br />considerations. <br /> The clouds on this day were too vigorous for conducting the mission reasonably. Wherever there was a <br />good cloud base updraft the clouds broke the cap and erupted upward leaving no opportunity for safe repeated <br />cloud penetrations. Working at higher levels than 14 kft would probably have taken the aircraft to heights where <br />the updrafts were too strong for save penetration. <br /> The flight tracks for this case are given in Figure 11. The seeded cloud is on the left where the spiral of <br />the seeder (Seed 3) in yellow and the passes of the monitoring aircraft (Seed 1) in greenare shown. The short <br />red segment superimposed on the green cloud physics flight track is the portion of the flight in which the SF <br />6 <br />gas was detected. <br />36 <br />