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<br />~ <br />'] <br />I <br />I <br />I <br />I <br />I <br />) <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />Using a computer-interfaced radar system allows us to quickly analyze clouds for hail <br />potential. The height of the 45 dBZ intensity contour within a cloud is evaluated against a "hail <br />threshold" based upon the height of the freezing level. The height of the 45 dBZ intensity level <br />within clouds is used as a test for determining whether crop-damaging hail potential exists in <br />storms and how destructive is its potential relative to other storms. It provides measurable data <br />crucial to making operational decisions regarding aircraft guida~ce during operations. For <br />instance, with a freezing level of 15,000 feet, the hail threshold would be 3 km higher, or roughly <br />25,000 feet. If radar showed a 45 dBZ signature in an unseededcloud at that height, or higher, it <br />would be considered to be able to produce crop-damaging hail at ground level. Generally, the <br />greater the 45 dBZ height is above the hail threshold, the larger is the size of the hailstone <br />formed, <br /> <br />Radar echoes are displayed as colored contours and viewed on a computer monitor. Since <br />1985 we have used the same basic concept of using the 45 dBZ level to determine hail in clouds. <br />This was done using a variety of methods to make the calculations: In earlier years calculations <br />were performed manually, at first using a calculator, then a couple years later using a computer, <br />then finally arriving at the system now employed. Although one person can operate the system, <br />operations work best when the meteorologist-aircraft controller can focus on aircraft guidance <br />while monitoring the continuous flow of significantly changing weather data while an assistant <br />operates the computer, collects weather data, updates the weather information requests of the <br />meteorologist and moves radar images to the Internet for pubic viewing, In the PPI mode the <br />background display shows the regional boundaries, counties, state lines, VOR navigational aids <br />and town locations. These are all helpful in providing guidance to aircraft at one time or another. <br /> <br />C, AIRCRAFT SEEDING OPERATIONS AND MAINTENANCE <br /> <br />The aircraft type used in 2001 for cloud base seeding and cloud-top seeding were: <br /> <br />6-single-engine Piper Aircraft Comanches, PA24-250 <br /> <br />I -twin engine turboprop Piper Cheyenne II <br /> <br />I-twin engine Beechcraft Baron, BE95C55 <br /> <br />We also kept another single-engine Comanche as a stand-by aircraft to be used in special <br />situations and for backup if maintenance on one of the regularly used aircraft rendered it out of <br />operation for more than a few hours. <br /> <br />All cloud base planes were equipped with Carley-type liquid fuel generators, one mounted <br />to each wing tip. Each generator holds 6 gallons ofa liquid seeding solution and burns AgI at 2.8 <br />grams per minute of operation which translates into 2,8 gallons ofliquid solution being burned <br />per hour of operation. Each full generator carries a total of 360 grams silver iodide and, ideally, <br />it should burn continuously for about 2 hours 9 minutes if correctly configured, This year cloud <br /> <br />20 <br />