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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />- 89 - <br /> <br />base concentration. Thus, if for a concentration of ice particles of 25t-l <br /> <br />the trajectory is increased in length by a factor of two and the <br />precipitation increased by a factor of lO over that for one ice paFticle per <br />liter, this is indicated as a point with an abiscissa of 2 and an ordinate <br />of 10. Fig. 3.8 shows the results for a west wind and Fi~. 3.9 for a <br />southwest wind. The results fOF ice particle concen1:T>;;It.iohO or 25 ~m(l ~OOJl-l <br /> <br />are essentially the same on these ~lots. <br /> <br /> <br />Although theFe is considerable scatter in the points shown in Fir,. 3.8 <br /> <br /> <br />a distinct trend can be disceI'tled. The results indicate that precipitation <br /> <br /> <br />can be increased by increasing the concentrations of ice particles provided <br />that the trajectories are not lengthened by more than about a factor of 2 <br />(i.e. 30 km). Also, the precipitation efficiency appears to be greater if <br /> <br />the increase in ice particle concentration occurs at low elevations (as <br /> <br />represented by the triangles) rather than at high elevations (as represented <br />by the circles). <br /> <br /> <br />The last conclusion is also seen in the results shown in Fig. 3.9. <br /> <br />However~ in this case the decrease in precipitation which might otherwise <br /> <br />accompany the long trajectories at high concentrations of ice particles is <br /> <br />off-set by the continued growth of the ice particles caused by further <br /> <br /> <br />lifting in the region downwind of the Cascade Divide. <br /> <br /> <br />Fig. 3.10 represents an entirely different way of presenting the same <br /> <br />basic data. Here the distributions of precipitation across the mountain for <br /> <br /> <br />the airflow corresponding to Figs. 3.3 and 3.5 are examined. The curve <br /> <br /> <br />labeled "rimed" shows the calculated distribution of precipitation if the <br /> <br /> <br />whole cloud had an ice crystal concentration of It -1. The curve labeled <br /> <br />