Laser-induced supersaturation and snow formation in a sub-saturated cloud chamber
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Calculation of the saturation ratio inside vortices formed below the filament in a sub-saturation zone in a cloud chamber was given. By mixing the air with a large temperature gradient, supersaturation was sustained inside the vortices. This led to precipitation and snow formation when strong filaments were created using short focal length lenses (f = 20 and 30 cm). However, when longer filaments were formed with the same laser pulse energy but longer focal length lenses (f = 50 and 80 cm), only condensation (mist) was observed. The lack of precipitation was attributed to the weaker air flow, which was not strong enough to form strong vortices below the filament to sustain precipitation.
KeywordsVortex Cloud Droplet Cloud Condensation Nucleus Cold Plate Focal Length Lens
The research work was supported in part by the following funding organizations: Natural Science and Engineering Research Council of Canada (NSERC), Canada Research Chairs, the Canada Foundation for Innovation, the Canadian Institute for Photonics Innovation, and le Fonds Québécois pour la Recherche sur la Nature et les Technologies (FQRNT), the National Basic Research Program of China (2011CB808100, 2010CB923203), National Natural Science Foundation of China (60921004, 11204329), Shanghai science and technology talent project (12XD1405200), the State Key Laboratory Program of Chinese Ministry of Science and Technology. TJW also acknowledges the support from 100 Talent Program of Chinese Academy Sciences and Shanghai Pujiang Program. Technical support from Mr. M. Martin of COPL, Laval University, is also acknowledged.
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