A STUDY OF ORGANIC CRYSTALS AS ICING NUCLEI.
Final rept., 1 Sep 61-30 Apr 62,
ARMOUR RESEARCH FOUNDATION CHICAGO ILL
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This investigation concerned a study of organic icing nuclei as cloud-seeding agents. Presently cloud seeding is accomplished by coverting liquid carbon dioxide to dry-ice pellets. The results of the laboratory work showed that organic compounds are promising. The following substances gave complete nucleation phloroglucinol at -2 C, trichlorobenzene at -12 C, d-raffinose at -14 C, trimesic acid at -15 C, and melamine at -15 C. In all, 32 organic compounds were investigated. Phloroglucinol, the most effective organic compound found, promises to exceed AgI in cloud-seeding efficiency, if an effective dispersal system can be developed. Preliminary dispersal tests with organic solvents showed promising results the nuclei appeared much more active when atomized from CH30H than from H2O. Theoretical analysis indicates that the activity of organic icing nuclei is determined by the configuration of the electric link-dipole moments in the molecules. The experiments to date indicate that organic compounds which exhibit ice-nucleating properties should possess more elements of molecular symmetry than ice and that the electric link-dipole moments should be arranged in such a fashion that the molecule will not have a resultant dipole. Author