ИСТИНА

A new cloud chamber was designed to investigate the formation and growth of ice crystals from vapor not only as the result of regulated temperature and water vapor supersaturation, but also due to interaction with neighbouring crystals and water droplets, similar to the conditions in natural supercooled clouds (e.g. Pruppacher and Klett 1997). The cloud chamber is cylindrical with a volume of about 0.67 m3 and placed in a temperature controlled (-1 to -20°C) cold lab several m3 in size. Nebulized water is continuously introduced to the cloud chamber forming a supercooled fog gradually moving upwards following a spiral trajectory. With regulated temperature and fog supply conditions the crystallization process is initialized by the addition of ice nuclei into the cloud chamber. After different growth times ice crystals are collected at the bottom and the top of the cloud chamber and are immediately photographed under a microscope. First systematic observations of the size and shape distribution of the ice crystals as a function of temperature and supersaturation are consistent with other literature data (e.g. Libbrecht 2005). The diverse crystal habits (e.g. plates, columns, hollow columns, dendrites) are formed successfully at different controlled conditions within the chamber and enable detailed studies to be carried out.