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<br />. <br /> <br />2.5: Droplet sizes. Fig. 2.5 shows the distribution in mean droplet <br /> <br />size for the clouds of 1979-1981. <br /> <br />Each measurement entering this <br /> <br />. <br /> <br />histogram represents one pass through a cloud, and the diameter that <br /> <br />is used is the mean diameter from the I-kIn region of maximum average <br /> <br />droplet concentration on that pass. Representative mean diameters were <br /> <br />. <br /> <br />only about 10-12 \.fil, and mean diameters almost never exceeded 20 l!m. <br /> <br />Fig. 2.6 shows a plot of the cumulative, distribution of the <br /> <br />volume-median diameter, often used to characterize the icing potential <br /> <br />. <br /> <br />of clouds; it also was seldom greater than 20 l!m. <br /> <br />Fig. 2.7 character i zes the size distributions. Of particular <br /> <br />interest is the frequency with which the concentrations of droplets <br /> <br />larger than 24 l! m exceed l/cm3, the threshold required for the <br /> <br />. <br /> <br />Hallett-Mossop (1974) ice ~ultiplication process. This requirement was <br /> <br />50 <br /> <br /> <br />100 <br /> <br />. <br /> <br />250 <br /> <br />200 <br /> <br />80 <br /> <br />~ <br />o , <br /> <br />150 <br /> <br />60 <br /> <br />lJJ <br />> <br />~ <br />...J <br />::::) <br />::IE <br />::::) <br />o <br /> <br />. <br /> <br />a: <br />lJJ <br />m <br />::IE <br />::::) <br />Z <br /> <br />100 <br /> <br />40 <br /> <br />20 <br /> <br />. <br /> <br />o <br />o <br /> <br />5 <br /> <br />10 <br /> <br />15 <br /> <br />20 <br /> <br />o <br />25 <br /> <br />MEAN DIAMETER (}Aom) <br /> <br />. <br /> <br />Fig. 2.5: Differential (solid line) and cumulative (dashed line) <br />distributions for the mean droplet diameters for the same data set as <br />in Fig. 2.4. <br /> <br />. <br /> <br />10 <br /> <br />. <br />