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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 />- 109 - <br /> <br />collected. Several were observed with diameters in excess of 5000 ~m and the <br /> <br /> <br />average size on the ground was about 3500 ~m. Because of the limiting width <br /> <br /> <br />of the continuous particle sampler these larger dendritic crystals could not <br /> <br /> <br />be collected intact from the aircraft. <br /> <br />Aircraft and ground observations indicated that stellar crystals were the <br /> <br />next largest star-like crystals. Several stellars over 3000 ~m in diameter <br /> <br />were observed and stellars as small as 250 ~m in diameter were collected from <br /> <br />the aircraft. The average diameter was about lOOO ~m in the air and about the <br />same on the ground. Crystals with broad branches ranged in diameter from about <br />300 ~m to 2500 ~m. The average size was about 800 ~m in diameter. Crystals <br /> <br />with sector-like branches rarely exceeded 2000 ~m in diameter and their average <br /> <br />size observed in the air was about 750 ~m in diameter. <br /> <br />Air and ground observations indicated that star-like crystals undergo <br /> <br />extensive break-up in the air. Isolated dendritic branches were very common. <br /> <br />Ground observations indicate that even crystals with sector-like branches <br /> <br />break-up in the air. However, larger percentages of star-like crystals were <br />collected intact in the air compared to crystals collected at the ground. <br />4.2.7 Stellar Crystals with Plates at the Tips of Branches (P2a) <br />Our aircraft observations confirmed the findings of Magono and Lee (1966) <br />that stellar crystals with plates at the tips of the branches grow between -l2 <br />to -l7OC. These crystals generally occurred individually in the air, but they <br />were also found as part of aggregates. When they were observed on the ground <br />they were generally individual crystals. <br />Air observations indicated that this type of stellar crystal ranged in <br /> <br />diameter from l500 to 4000 lJm. Thus~ there was a tendency for only larger <br /> <br />