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<br />well in demonstrating the potential of dynamic seeding concepts in Thailand. As a <br />consequence, the design will serve as the basis for the design of the Phase 2 cold cloud <br />seeding experiment. Therefore, the sample obtained so far can be combined with the sample <br />that will be obtained during the course of the Phase 2 effort. <br /> <br />2.6 General Experimental Guidelines <br /> <br />According to Flueck (1986), the objectives in any experimental effort should be to address an <br />apparently "solvable" problem and to achieve a "believable" solution. The characteristics of <br />a potentially solvable problem include being able to state the problem, assuring that the <br />problem is amenable to quantitative analysis, and ensuring that some useful results will be <br />obtained within the constraints of the available resources. The characteristics of a believable <br />solution depend on the plausibility ofthe theory or conceptual model that is offered to explain <br />the processes of interest, and on the cn~dibility of the supporting statistical evidence. Based <br />on experience in Thailand, a solvable problem-the production of more rain from cold <br />clouds-has been identified, and addressing it with the proposed experiments should lead to <br />a credible solution. <br /> <br />2.7 The Conceptual Model for the Cold Cloud Seeding Demonstration Project <br /> <br />The dynamic seeding conceptual model as discussed most recently by Rosenfeld and Woodley <br />(1993) will serve as the model for the Thai demonstration experiments. The main departure <br />of the new dynamic seeding model from the "classical" model of the past (Woodley, et al., <br />1982) is the realization that dynamic: seeding can also produce a substantial increase in <br />convective rainfall without a large increase in the maximum height of the seeded entity. <br /> <br />New and old scientific findings from a number of research projects support the steps in the <br />new conceptual chain. These findings have been combined with the new results to synthesize <br />a revised conceptual model for dynamie seeding that in no way contradicts the precepts of the <br />old, but merely builds and expands on them in places where physical insight was lacking <br />previously. Part 1 of appendix B provides a complete discussion of the conceptual model that <br />is guiding the Thai experiments. <br /> <br />2.8 Specification of the Design Variables <br /> <br />2.8.1 Experimental unit <br /> <br />The experimental unit will consist of the convective cells that receive real (i.e., AgI flares) or <br />simulated treatment within a circle having a radius of 25 kilometers and centered at the <br />location of the convective cell which qualified for the first treatment. This unit will be <br />advected with the mean speed and direction of the precipitation echoes in its vicinity. The <br />unit will encompass nearly 2,000 square kilometers, which is about the largest area that can <br />be covered effectively with one seeder aircraft. <br /> <br />The selection and termination of the experimental unit will be based upon the following <br />requirements: <br /> <br />1. A preliminary sampling pass shall establish that convective cells in the area contain <br />maximum (l-second values) liquid water contents of at least 1.0 gram per cubic meter <br />and maximum (l-second values) updrafts of at least 1,000 feet per minute (i.e., > 5 <br />meters per second), as determined from real-time readouts aboard the aircraft. <br /> <br />9 <br />