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<br />estimate of cloud top if the storm is not convective. Under convective <br /> <br />conditions, depending on where the radiosonde went through the cloud. <br /> <br />cloud top was extremely variable. Comparisons of the rawinsonde-derived <br /> <br />cloud top with that from radar showed little agreement. Normally the <br /> <br />radar showed tops considerably lower than the rawinsonde and in some <br /> <br />cases showed no cloud at all. Since both the Pagosa Springs and the BOR <br /> <br />radars had a wave length of 3.2 centimeters and a peak power output of <br /> <br />about 50 kw, it is doubtful that they were measuring cloud top in the <br />I <br />I <br />light snowfall which occurs in the upper portion of the orographic clouds <br /> <br />, <br />near Wolf Creek Pass. For this study, rawinsonde data were used exclus- <br /> <br />ive1y for estimating cloud top. Figures Al through A22 in Appendix A <br /> <br />show the rawinsohde data plotted and cloud tops indicated for the periods <br /> <br />when crystal data were collected. <br /> <br />Ice nucleus data from the three ice nucleus counters were combined to produce <br /> <br />the spectra in Figures Bl-B22 in Appendix B. The solid line in the figures <br /> <br />indicates a theo~etica1 estimate of natural ice nucleus concentrations. <br /> <br />Most seeded events will show numerous concentrations to the left of the <br /> <br />line while most hatura1 events will show concentrations to the right of <br /> <br />the line. Since the minimum detectable concentration for the CSU Rapid <br /> <br />Expansion Chamber is .1 per liter, zero counts were plotted as .01 per <br /> <br />liter. Plots of natural ice nuclei allow one to estimate the concentrations <br /> <br />of ice crystals to be expected in a cloud without any type of secondary <br /> <br />or artificial ice production. <br /> <br />-15- <br />