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<br />B-2 <br /> <br />Primary analyses were performed for 388 "rain days" -- days on which at least 0.1 mm. of <br />rain was recorded in a "buffer zone" south of and adjacent to the target area (but presumably <br />"up wind" enough not to be affected by seeding). Of the rain days, by random selection, 209 <br />were seeded, while 179 were not seeded. <br /> <br />The primary statistic selected to evaluate rainfall contrasted rainfall in the target under <br />seeding with rainfall in the target under nonseeding, and also rainfall in an upwind control area <br />under seeding and npnseeding (double ratio statistic). <br /> <br />* Alberta hail project · <br /> <br />The Alberta Hail Project was conducted during summer seasons, 1974-1976, to learn <br />effects of seeding large cumulo-nimbus clouds upon hail production. While initially employing <br />randomization, changes in design in 1974 and thereafter had the effect of aborting the random- <br />ized design. By 1977, all storms were being seeded. The summary statistic was hail volume, <br />assessed by measures taken from mobile hail vehicles, a mobile sounding vehicle, and a cloud <br />photogrammetry team. <br /> <br />* Santa Barbara rain experiment II * <br /> <br />Phase 1 (of Santa Barbara II) was designed with intentions that would now be described as <br />confirmatory in the main target area and exploratory in the extended (downwind) area. It <br />employed a single high output source of AgI on a 3000-ft. ridge, which was only employed <br />while a convective rain band (selected for seeding) was passing. There were 0967-1971) 56 <br />seeded and 51 not seeded bands. Randomization was unrestricted and by rain-band (rain-bands <br />provide about 3/4 of the precipitation in Santa Barbara County). <br /> <br />Since seeding in phase 1 appeared ineffective when the base of convection was at or above <br />3000 feet, phase 2 was designed for airplane seedin.g at an appropriate height for each band. <br />Safety considerations forced the seeding to be conducted 60 miles further west (off the Coast). <br />Phase 2 was suspended before planned completion, with only 18 seeded bands and 27 unseeded <br />ones 0971-1974). <br /> <br />* South Africa hail suppression program · <br /> <br />This unrandomized project, begun in 1972 and continuing, entails seeding of all potential <br />hail storms in the vicinity of Nelspruit, Transvaal, Republic of South Africa. The primary <br />response variable is insurance claims for crop damage. Seeding effectiveness has been assessed <br />by comparing apparent crop damage for storms in experimental years with that of earlier years. <br /> <br />* North Dakota pilot project * <br /> <br />This randomized study was conducted during summer seasons, 1969 through 1972. It was <br />designed to assess effects of seeding both upon rainfall and upon hail fall, with rain gauges <br />measuring rain and crop insurance claims and hail pads measuring hail. The study encompassed <br />368 experimental days, 277 seeded, 91 unseeded. <br /> <br />* Tasmania * <br /> <br />This is a randomized study of the effects of seeding on rainfall, year-round, in Central <br />Tasmania. It was conducted in even-numbered years from 1964 to 1970, with a target area, <br />mainly on a plateau of 2500 to 3000 feet altitude with peaks to 5000 feet in the western part, a <br />subsidiary area and three control areas, all of maximum dimension 30 to 100 miles. Seeding <br />was by aircraft, directly into the cloud. <br />