Effects of initial humidity and temperature on laser-filamentation-induced condensation and snow formation
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We investigated the effects of initial humidity and temperature on the formation of water condensation and various snowflake patterns by firing high-repetition filaments of femtosecond Ti-sapphire laser pulses at 9 mJ/50 fs per pulse into a cloud chamber. While adjusting initial temperature and humidity distributions near the filaments, snowflakes and ice particles with various shapes and sizes were observed on the bottom cold plate. In addition, significant differences were found in the weights of the laser-induced snow below the filament center. From those data, initial conditions of low temperature (<−15 °C) and high humidity (relative to water RHw > (90 ± 11) % and to ice RHi > (120 ± 15) %) were found being important to assist an efficient laser-filamentation-induced condensation and snow formation.
This work was supported by the National Basic Research Program of China (Contract No: 2010CB923203, 2011CB808100), National Natural Science Foundation of China (Contract Nos: 60921004, 10974214, 61008011), Shanghai science and technology talent project (12XD1405200), the State Key Laboratory Program of Chinese Ministry of Science and Technology. See Leang Chin acknowledges the support of Canada Research Chairs, Natural Science and Engineering Research Council, and Quebec Fund for Nature and Technology Research.