| Laboratory experiments are designed to obtain quantitative data describing ice nucleation by specific aerosols used operationally for weather modification in China. Seven kinds of AgI-type pyrotechnic have been detected in the 1m~3 isothermal cloud chamber (CAMS) to study their ice nucleating properties. In addition, the measuring results of seven seeding agents released with size distribution are discussed also.The main conclusions are summarized as follows:(1) The test process and experimental properties of the new 1m~3 ICC (CAMS) are detected. The results show that it is superior to other cloud chambers by its temperature and experimental property. Its testing results are scientific, creditable and comparable. The testmg approach is standardized.(2) The ice nucleation effectiveness for several AgI-type seeding agents in common use in weather modification of China is compared. These nucleus aerosols are then fully characterized for effectiveness and rates of nucleation from -4℃to -20℃in the isothermal cloud chamber. The nucleating properties of several types of AgI pyrotechnic made by different formulations are analyzed and compared by using the testing data obtained from the chamber. Its effectiveness will be increase in warmer temperature when adding CuI in pyrotechnics component.(3) From the electron microscopic analyses, the size distributions of the particles produced from all seven types of flares were found to be similar. For each of pyrotechnics, more than 98% of AgI effluent concentration is contained in particles< 0.5μm in diameter, and more than 90% is contained in particles≤0.3μm. Different kinds of AgI-type pyrotechnic have different size distribution. Based on TECNAI F30 micrographs of 7 kinds of AgI-type pyrotechnics particles, several less AgI particles adhered on a KCl particle and the structure characteristics is maybe the key reason that caused a high nucleating effectiveness. For seven kinds of AgI agents, their thresholds temperature change in the range of -3.5℃～-4.4℃. Their differences are relatively small, in other words, the temperature thresholds of AgI pyrotechnics are mainly decided by the physical and chemical property of AgI itself.(4) The chemical kinetic approach is employed in this study. The results show that the nucleating rate, efficiency and even the nucleating mechanism of these pyrotechnics are different. For different aims of the weather modification operating and different clouds, we shall choose different seeding agents which they are not same in the nucleating rates.(5) Basing on the microscope recording data, some microphysics characteristics were studied in the paper. It includes the deposition growth, the growth rate of single ice crystal, the shape characteristic of ice crystal, etc.
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