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<br />Pa g e 22 <br /> <br />A manual 35 mm camera will provide slides of the cloud cover over <br /> <br />the Rim east of the rawinsonde site. These will be taken near <br /> <br />radiosonde release times. <br /> <br />Video cameras on the instrumented aircraft will record cloud <br /> <br />formations during missions. <br /> <br />10. Pibal observations <br /> <br />Pilot balloons (Pibals) will be periodically released and <br /> <br />optically tracked from the Happy Jack site to obtain wind speed <br /> <br />and direction profiles. A small shelter will be installed at the <br /> <br />, <br />site, which will have folding roof sections that can be opened. <br /> <br />It will be used to inflate balloons and to house the <br /> <br />Warren-Knight theodolite with which tracking will be <br /> <br />accomplished. Prior to release, the balloons will be inflated <br />inside the shelter with a precise amount of free lift, which will <br /> <br />produce a known ascent rate. Therefore the height of the balloon at <br /> <br />each minute after release can be estimated quite accurately as long <br /> <br />as no updrafts or downdrafts are encountered. Following the balloon <br /> <br />release the operators will start optical tracking using the theodo- <br /> <br />lite. A timer will provide an audible tone at one minute intervals, <br /> <br />and at these times vertical and horizontal angle data will be read <br />