PARTICLE SIZE DISTRIBUTION AT 110,000 FT 143 Table 3—- MEDIAN PARTICLE SIZE Flight No. Estimated particle diameter, yp 2556, 2562, 2569, and 2572 2611 T-781-A T-796-A 0.002 0.008 0.13 0.008 HASL is continuing its efforts in stratospheric particle studies to verify the findings reported here and to obtain information about particle size distributions at other balloon-sampling altitudes. A compact, lightweight electrostatic precipitator is now being developed for the specific purpose of collecting samples for making the appropriate measurements. The design of this sampler will eliminate the causes of uncertainties in the quality of samples, particularly with respect to sample contamination by nonstratospheric particles. REFERENCES 1. C. E. Junge and J. E. Manson, Stratospheric Aerosol Studies, J. Geophys. Research, 607): 2163-2182 (1961). 2. J. P. Friend (Ed.), The High Altitude Sampling Program, Report DASA~-1300, Vol. 5, Supplementary HASP Studies, Isotopes, Inc., Aug. 31, 1961. 3. M. Lippmann (Comp.), Stratospheric Monitoring Program, Summary Progress Report, February 1961—April 1962, USAEC Report NYO-9675, Del Electronics Corporation, Sept. 10, 1962.

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