Observation of Falling Motion of Columnar Snow Crystals

[摘要] Free-fall pattern and velocity of columnar snow crystals were observed by the stereophotogrammetric method. The experimental formula between falling velocity and mass was obtained for the various types of columnar crystals. The rotation about vertical axis and the oscillation in vertical plane were observed for all of the rimed columnar crystals. The period of oscillation was about one-half that of rotation and the non-dimensional frequency of rotation increased in proportion to Reynolds number.Although the rimed columns fell with vertical path, about 50% of the rimed needles and sheaths fell with clear spiral trajectory.

[学科分类] 大气科学