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<br />\ <br /> <br />'"' <br /> <br />I) -14 0 C and warmer produce up to 1Ol6 effective nuclei hr -l at <br />-150 C per generator site (up to 140 gm hr-1) <br />2) -150 C to -230 C produce 1016 effective nuclei hr -I at -200 C <br />per generator site (20 gm hr -I) <br /> <br />The rate for -140 C and warmer was lower than model specifications, <br />but was deemed reasonable at this time as a design parameter because of <br />possible ice multiplication effects at warm temperatures. The high generator <br />output (up to 140 gram/hour) at the warm temperatures may be physically dif- <br />ficult to obtain with normal ground generators. About 40 hours of the warmer <br />temperature range (-140 C and warmer) are expected in a typical winter. <br /> <br />2.4 GENERATOR SELECTION PROCEDURE <br />During the 1970-71 season, appropriate generators were operated for <br />seeding the target areas according to wind direction and speed. The generators <br />were started one hour prior to the beginning of an experimental day or an appro- <br />priate period, and generator operation was terminated two hours prior to the <br />end of an experimental day or appropriate period. The generators were operated <br />in accordance with the wind constraints delineated in Table 2-1. The Durango " <br />radiosonde was used to monitor the local 700 mb wind conditions over the tar- <br />get area. ~ <br />The procedure for the selection and targeting of generators for the 1971- <br />72 season was changed twice during the season. The first procedure was based <br />on a computation procedure developed by Mr. Art Rangno, EG&G, Inc. The <br />basic concept of this procedure is presented in Figure 2-1. Computations for <br />each generator site were made from the various wind directions within the <br />operating limit envelope and a table of generator limits was constructed (Figure <br />2-2) to provide the total number of generators available for any given wind <br />direction. It was not mandatory to request all of the generators listed, but in <br />practice it was generally done this way. The guiding parameters for using <br />the table were the resultant vector of the winds from the surface through 10,000 <br />feet MSL, (plotted on a hodograph from the project rawinsonde data) and the <br />12,000 foot MSL wind speed. This first procedure remained in effect until <br />mid-January 1972. <br />The procedure in effect for the remainder of the five-year Proj ect is <br />described in the following subsections: <br /> <br />2-6 <br />