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<br />- . , <br /> <br />or. the aircraf~ measured alci~~de, pressure, indicated turbulence, posi~ion, <br /> <br />.~- <br /> <br />temperature, dew poiat, and winds. <br /> <br />The aircraft also carried Johnson-williams. <br />I <br /> <br />'"'"_ I <br /> <br />and CSIRO liquid water meters, a Rosemount icing rate meter, an inertial <br /> <br />J <br /> <br />navigation syste3, an KCAR ic~ nucleus counter, a Particle Measuring System <br /> <br />(P~S) FSSP in the 3-4~ ~m range with 3 ~m resolution, and the following PMS <br /> <br />Optical Array P~obes: ID-C operated in the range 12.5-187.5 ~m with 12.5 ~m <br /> <br />resolution, 2D-C in the 25-800 pm range with 25 pm resolution, and 2D-P in the <br /> <br />200-6400 ~m range with 200 ~m resolution (Kno11enberg, 1981). The research <br /> <br />aircraft was capable of measuring the evolution of a packet of ice crystals as <br /> <br />it drifted dOw~wind. Bu i~tegrating true airspeed and heading, the computer <br /> <br />on the research aircraft could direc~ the pilot to make repeated penetrations <br /> <br />of a point drifting with the wind (Cooper and Lawson, 1984; Huggi~s and Rodi, <br /> <br />1985). <br /> <br />The seeder aircraft was a Cessn~ Aero Commander and burned the AgI NH41 <br />I(~-;'-\;'f" ~"}.r:'{ ,.tta..:~\.;"v..J \~ o-dh.~~ <br /> <br />NH4CI04 in acetone in a1Carly type generatoi\mounted on the fuselage. The AgI <br />J <br /> <br />was released at a rate of 0.4 g km-l, using a generator containing a 3 percent <br /> <br />by ~eight solution of AgI KP.~I NH~CIO~ with the arr~onium perchlorate at a 30 <br /> <br />Dole ratio. This solution was chosen since tests indicated it would produce <br /> <br />ap?roxi~a~e1y 1013 nuclei g-l at -6~C (DeMott et al., 1983). with th~s <br /> <br />activity a rough calculation or the ICe resulting from seeding can ~e made. <br /> <br />Assurr:ing that: the AgI "cylinder" expands at 1.0 m s-l and that 80 percent of <br /> <br />the ice nuclei have activated (De~ott: et al.! 1983), the ICC would be <br /> <br />approximately 10 L-~ aft:er 10 mi:1. H01.lever, if as DeHoet et al. suggest, <br /> <br />contact nucleation is t~e pri~ary n~CLeatlon w.echanism for AgI NH~I, then t~~s <br /> <br />estireate is too high. Inclucing the rate at which ice nuclei are scavenged by <br /> <br />c~oud droplets (Slir,n, 1971), and aS5~T<ing 100 cm-3 of 5 pm cloud drops, <br /> <br />instead or the 2000 to 4000 crr:-3 in the cloud c:tamber where <br /> <br />the ma~erial <br /> <br />...:u~ <br /> <br />;:; <br />