Morphology of single snow crystals growing in air at low temperatures

• Main Authors: Takehiko Gonda, Tetsuya Koike
• Format: Report
• Language: English
• Published: Faculty of Science and Technology, Science University of Tokyo 1982
• Subjects: Antarc*; Antarctica; Memoirs of National Institute of Polar Research; Polar Research
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=1346; http://id.nii.ac.jp/1291/00001346/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=1346&item_no=1&attribute_id=18&file_no=1

In order to study the morphology and the growth mechanisms of single snow crystals observed in polar areas, ice crystals were formed in air at 1.0 atm at -30℃ and various constant supersaturations. At low temperatures, minute plate-like and column-like ice crystals are formed at the same time under the same environmental conditions; the morphology of these crystals depends not only on temperature but also on supersaturation, crystal size and macroscopic surface structure. From our experimental results, it is inferred that on diamond dust particles observed in Antarctica, when columnar ice crystals are predominantly observed, the supersaturation is lower than about 2%, while when plate-like ice crystals are predominantly observed, the supersaturation is higher than about 2%. Moreover, it is inferred that long solid prisms and rectangular snow crystals observed in polar areas grow by the screw dislocation mechanisms at a supersaturation lower than about 2%.