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<br />I <br />1/ ' <br /> <br />/ <br /> <br />18 <br /> <br /> <br />Figure 23.-Snow-pillow and Electrical Readout Equipment. <br /> <br />PARK RANGE ATMOSPHERIC WATER RESOURCES PROGRAM <br /> <br />snow-rate and a superimposed saw-tooth can be <br />totalized to give total precipitation. The gage is <br />well insulated by 2Y2-inch polyurethane slabs. While <br />the evaporation problem at low snow-rates is of no <br />great importance to our experiment, the dynamic <br />response of the instrument at high snow-rates is a <br />limitation. The time constant to a step function <br />of snow-rate with amplitude of 0.2 inch H20/hr. <br />or so is of the order of 5 minutes; this has the effect <br />in the power spectrum analysis of erasing compon- <br />ents with periods of less than 20 minutes. We <br />know from experience with rain-rate histories that <br />this part of the spectrum is important, and so have <br />been experimenting casually with ways of reducing <br />the time constant to the order of one minute. <br />Figure 26 shows a data sample. <br />The tipping-bucket rain-rate gage used for sum- <br />mer operations, figure 27, is the same as the heated <br />gage, but without the heat transfer time-constant <br />difficulty. Full scale is adjustable between 1 and <br />10 inches H20/hr. <br />The optical snow-rate gage!, figure 28, consists <br />of a light source, a 3-foot transmission path, a CdS <br /> <br />-I <br /> <br />J <br /> <br />1 Zopf, D" 1965: "Engineering Aspects of Weather Modifica- <br />tion". Proceedings of Western Snow Conference, 1965 (to be <br />published). <br /> <br />-- --..... <br /> --- <br /> - <br /> - - <br /> n <br /> -- <br /> -- <br /> -- <br /> -- -- <br /> -, <br /> ex) q>- 0 - <br /> .... .... <br />. . . . . . . . . . . . . . . . . . . . . <br />- _._--- - --~~- _.- .-.. ---_._._---- -------- -~ <br /> <br />0.5 in. H.O <br /> <br />~IHOUR~ <br /> <br />Figure 24.-Example of Snow-pillow Output -0.5 inch H"O Full Scale. <br />