Seeding Condition of Precipitation Enhancement Revealed by Multiple Spectral Data of Satellite. I: Convective Clouds

Based on the technology of the satellite retrieval and comprehensive analysis methodology of cloud microphysical properties, different microstructure and precipitation formation processes for convective clouds were analysed so as to investigate their seeding ability and seeding mode. Four kinds of convective clouds were summarized as seedable convective cloud systems. The first is the deep heavily polluted convective clouds, the hygroscopic nucelli or AgI can be seeded when the particle effective radius at the cloud base is less than 7 μm, and the zones of diffusional growth and calescence growth are rather deep and thin, separately, there exists no zone of rainout, the glaciation temperature is below than -30℃, the temperature corresponding the depth of precipitation initiation covers 20℃ which extends from the base to the level of precipitation formation. The second is the hailstorm clouds with strong updraft, also the hygroscopic nucelli or AgI can be seeded when the strong convective characteristic can be seen in the appearance, the growth rate for different growth zones are rather low, there is no zone of rainout, the glaciation temperature is below than -30℃, and there exists an obvious declining zone of the particle effective radius around the cloud tops. The third is convective clouds with the strong updraft and heavy precipitation; AgI can be seeded near the isotherm of 0℃ so as to prompt the cold cloud precipitation when the drop near the cloud base is larger, usually than 10 μm, and the calescence growth is fully developed; the glaciation temperature is below than -30℃; the delay of the glaciation is obvious; the cold cloud precipitation does not fully develop. The last is the shallow polluted convective clouds; the hygroscopic nucelli can be seeded when the drop near the cloud base is less than 10 μm, and the zone of diffusional growth is deep; the zone of calescence growth is rather thin; there is no zone of rainout; the particle effective radius on the cloud top is less than 14 μm; the cloud depth ranges between 3 km and 6 km.