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<br />telephone was still the communication device between the project director and pilots not based at <br />the project headquarters (Lakin), but a beeper system allowed the pilots some flexibility. <br /> <br />Project meteorologists collected and analyzed weather data and prepared daily seedability forecasts. <br />Aircrews were briefed on anticipated storm development. The aircrews usually did not include <br />meteorologists, but the pilots were trained to recognize clouds that have the potential for <br />developing into hail storms. Because the project radar cannot detect clouds until precipitation has <br />already begun, actual aircraft launch was based on visual observation of potentially seedable clouds <br />by either the project meteorologists or the pilots themselves. However, all seeding was performed <br />under positive aircraft control by the radar meteorologist, with appropriate input from the pilots. <br />The weather was continuously monitored throughout the day. <br /> <br />2.2 Seeding Materials <br /> <br />Both dry ice (solid carbon dioxide) and AgI (silver iodide) have been used. Dry ice was released <br />from high performance aircraft flying near cloud top. Three types of AgI devices have been used <br />in Kansas: (1) liquid-fueled AgI generators that release seeding material as the aircraft flies near <br />cloud base, (2) AgI pyrotechnic flares that release seeding material as the aircraft flies near cloud <br />ba.~e, and (3) droppable AgI pyrotechnic cartridges that are ejected from the aircraft flying near <br />cloud top, releasing seeding material as they fall. Each AgI device has its advantages and <br />disadvantages. The interested reader is referred to Dermis [4] for additional information on seeding <br />devices. Table 2.4 indicates the seeding devices used each year. <br /> <br />Table 2.4.- Seeding devices used in the Western Kansas Weather Modification Project. <br /> <br />75 76 77 78 79 80 81 82 83 84 85 <br /> <br />------------------------------------------- <br /> <br />AgI bum-in-place <br />flare X X X X X X X <br />AgI droppable <br />cartridge X X X X X <br />AgI-acetone X X X X X X X X X X X <br />Dry Ice x x x x <br /> <br />o <br /> <br />Data from the nine years 1977-85 were examined to detennine the relationship between the rainfall <br />patterns and the amount of seeding material released. During those years, three seeding modes <br />were possible: (1) AgI alone, (2) dry ice alone, and (3) both dry ice and AgI. AgI alone was the <br />most frequent mode, but the total mass of dry ice released was almost six times that of AgI. For <br />this analysis, the seeding material released during each seeding mission was determined and the <br />data categorized in several ways: (1) all seeding missions (comprising the total seeding material <br />released for the given time period), (2) AgI missions only, (3) dry ice missions only, (4) all <br />missions releasing AgI (which includes AgI alone and AgI-dry ice missions), and (5) all missions <br />releasing dry ice (which includes dry ice alone and AgI-dry ice missions). Both categories 4 and 5 <br />contain the mixed-mode seeding missions. <br /> <br />. <br /> <br />7 <br />