Scanning electron microscopy and molecular dynamics of surfaces of growing and ablating hexagonal ice crystals

作者：Pfalzgraff W C; Hulscher R M; Neshyba S P^*

来源：Atmospheric Chemistry and Physics, 2010, 10(6): 2927-2935.

DOI：10.5194/acp-10-2927-2010

We present the first clearly resolved observations of surfaces of growing and ablating hexagonal ice crystals using variable-pressure scanning electron microscopy. The ice surface develops trans-prismatic strands, separated from one another by distances of 5-10 mu m. The strands are present at a wide range of supersaturations, but are most pronounced at temperatures near the frost point. Pyramidal facets consistent with Miller-Bravais indices of 10 < span style='border-top: 1px solid #000; color: #000;'> 1 1, and possibly also 20 < span style='border-top: 1px solid #000; color: #000;'> 2 1, are associated with ice growth under these conditions. A molecular-dynamics model of a free-standing ice I(h) nanocolumn containing 8400 water molecules does not develop trans-prismatic strands, suggesting these features originate at larger spatial or temporal scales. The possible relevance of these surface features to cirrus ice is discussed.

• 出版日期2010