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Inadvertent weather modification and Los Angeles smog

1972; Elsevier BV; Volume: 39; Issue: 1 Linguagem: Inglês

10.1016/0021-9797(72)90162-2

1095-7103

George M. Hidy, W Green, A.J. Alkezweeny,

Climate variability and models

The potential mechanisms for inadvertent weather modification by anthropogenic aerosols are reviewed briefly. Within this framework, limited measurements of cloud condensation nuclei and ice nuclei taken during the 1969 Pasadena experiment are discussed. The condensation nuclei observations were made with an MRI thermal diffusion counter and the ice nuclei were made using a Millipore filter technique. The results suggest that the cloud condensation nuclei counts are in the range of 103cm−3 at 0.5% water vapor supersaturation, and they increase during the day in rough correspondence with the second moment of the aerosol distribution. On the other hand, the ice nuclei counts are in the range of 200 m−3 at 18°C, and appear to decrease during the day. Such diurnal behavior may be related to the “poisoning” of otherwise active nuclei in the presence of organic material in the Los Angeles atmosphere.