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<br />Users were so interested in results that, for commercial operators there was no room for <br />randomization or scientific method. As a result, rigorous proof of a seeding effect in the <br />commercial cloud-seeding projects was not pursued. Even today, the words "weather <br />modification" and "cloud seeding" are met with some skepticism. <br /> <br />In the late 1950s, some projects were developed with support of governmental agencies <br />and although the experiments (e.g., the Missouri Project, Whitetop) ran for several <br />seasons, the results were mixed. None of the experiments provided incontrovertible <br />evidence that seeding was effective. Even in 1964 after many more projects were <br />completed, the National Research Council (NRC) concluded that precipitation from <br />orographic storms would not be increased significantly by seeding and that eventually <br />relevant processes could be understood and usefully applied. "The timescale required for <br />success may be measured in decades" (NRC, 1964). An NRC report in 1966 presented <br />results with an "indication of positive effect." In general, the authors of the time found <br />that cloud seeding experiments had not yet provided the evidence required to establish <br />scientific validity, though the prospects were promising and worth pursuing. <br /> <br />One of the references for this paper is Critical Issues in Weather Modification Research <br />prepared by the National Research Council of the National Academy of Sciences in 2003 <br />(NRC Report). To paraphrase the 2003 report, the Committee on the Status of and Future <br />Directions in U.S. Weather Modification Research and Operations finds little reason to <br />differ from the findings of the 1964 and 1966 studies. This is due in part to the lack of <br />concerted research in weather modification. In the three decades since the last NRC <br />report there have been improvements in the understanding of cloud processes and <br />significant development in tools and techniques, including remote sensing and <br />computing. These improvements, plus new methods for physically evaluating the <br />impacts of cloud seeding, mandate a fresh look at the status and potential of weather <br />modification. <br /> <br />There are, however, others that do not subscribe to this point of view. List (2005) <br />reviews the NRC Report and finds it flawed in several ways. He submits that the level of <br />accuracy of experiments that WxMod researchers face is higher than that of all other <br />meteorology and atmospheric physics disciplines, which he calls a double standard. <br />Other criticisms of the NRC Report include: the use of old, outdated and misleading <br />criteria; lack of specific criticisms of the science; no discussion of the role of statistics; <br />and the lack of identifying the progress and achievements made in recent decades. The <br />Weather Modification Association takes issue with the NRC Report as well, and its <br />perspective is presented in the section below under Policy Statements. <br /> <br />Meanwhile, numerous short and long-term operational seeding programs have been <br />ongoing with program proponents claiming meaningful, measurable results. These <br />operations programs are described in Section II below. <br /> <br />-2- <br />