Lateral facet growth of ice and snow – Part 1: Observations and applications to secondary habits
<p>Often overlooked in studies of ice growth is how the crystal facets increase in area, that is, grow laterally. This paper reports on observations and applications of such lateral facet growth for vapor-grown ice in air. Using a new crystal-growth chamber, we observed air pockets forming at...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2019-12-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/19/15285/2019/acp-19-15285-2019.pdf |
| _version_ | 1828544513747976192 |
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| author | J. Nelson B. D. Swanson B. D. Swanson |
| author_facet | J. Nelson B. D. Swanson B. D. Swanson |
| author_sort | J. Nelson |
| collection | DOAJ |
| description | <p>Often overlooked in studies of ice growth is how the crystal facets increase in area, that is, grow laterally. This paper reports on observations and applications of such lateral facet growth for vapor-grown ice in air. Using a new crystal-growth chamber, we observed air pockets forming at crystal corners when a sublimated crystal is regrown. This observation indicates that the lateral spreading of a face can, under some conditions, extend as a thin overhang over the adjoining region. We argue that this extension is driven by a flux of surface-mobile molecules across the face to the lateral-growth front. Following the pioneering work on this topic by Akira Yamashita, we call this flux “adjoining surface transport” (AST) and the extension overgrowth “protruding growth”. Further experiments revealed other types of pockets that are difficult to explain without invoking AST and protruding growth. We develop a simple model for lateral facet growth on a tabular crystal in air, finding that AST is required to explain observations of facet spreading. Applying the AST concept to observed ice and snow crystals, we argue that AST promotes facet spreading, causes protruding growth, and alters layer nucleation rates. In particular, depending on the conditions, combinations of lateral- and normal-growth processes can help explain presently inexplicable secondary features and habits such as air pockets, small circular centers in dendrites, hollow structure, multiple-capped columns, scrolls, sheath clusters, and trigonals. For dendrites and sheaths, AST may increase their maximum dimensions and round their tips. Although these applications presently lack quantitative detail, the overall body of evidence here demonstrates that any complete model of ice growth from the vapor should include such lateral-growth processes.</p> |
| first_indexed | 2024-12-12T02:32:09Z |
| format | Article |
| id | doaj.art-87c53f697be441eba1cba7ede0217421 |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-12-12T02:32:09Z |
| publishDate | 2019-12-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-87c53f697be441eba1cba7ede02174212022-12-22T00:41:22ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242019-12-0119152851532010.5194/acp-19-15285-2019Lateral facet growth of ice and snow – Part 1: Observations and applications to secondary habitsJ. Nelson0B. D. Swanson1B. D. Swanson2Redmond Physical Sciences, Redmond, WA 98052, USAEmeritus Department of Earth and Space Sciences, University of Washington, Seattle, WA 98195, USALaucks Foundation Research, Salt Spring Island, BC V8K2E5, Canada<p>Often overlooked in studies of ice growth is how the crystal facets increase in area, that is, grow laterally. This paper reports on observations and applications of such lateral facet growth for vapor-grown ice in air. Using a new crystal-growth chamber, we observed air pockets forming at crystal corners when a sublimated crystal is regrown. This observation indicates that the lateral spreading of a face can, under some conditions, extend as a thin overhang over the adjoining region. We argue that this extension is driven by a flux of surface-mobile molecules across the face to the lateral-growth front. Following the pioneering work on this topic by Akira Yamashita, we call this flux “adjoining surface transport” (AST) and the extension overgrowth “protruding growth”. Further experiments revealed other types of pockets that are difficult to explain without invoking AST and protruding growth. We develop a simple model for lateral facet growth on a tabular crystal in air, finding that AST is required to explain observations of facet spreading. Applying the AST concept to observed ice and snow crystals, we argue that AST promotes facet spreading, causes protruding growth, and alters layer nucleation rates. In particular, depending on the conditions, combinations of lateral- and normal-growth processes can help explain presently inexplicable secondary features and habits such as air pockets, small circular centers in dendrites, hollow structure, multiple-capped columns, scrolls, sheath clusters, and trigonals. For dendrites and sheaths, AST may increase their maximum dimensions and round their tips. Although these applications presently lack quantitative detail, the overall body of evidence here demonstrates that any complete model of ice growth from the vapor should include such lateral-growth processes.</p>https://www.atmos-chem-phys.net/19/15285/2019/acp-19-15285-2019.pdf |
| spellingShingle | J. Nelson B. D. Swanson B. D. Swanson Lateral facet growth of ice and snow – Part 1: Observations and applications to secondary habits Atmospheric Chemistry and Physics |
| title | Lateral facet growth of ice and snow – Part 1: Observations and applications to secondary habits |
| title_full | Lateral facet growth of ice and snow – Part 1: Observations and applications to secondary habits |
| title_fullStr | Lateral facet growth of ice and snow – Part 1: Observations and applications to secondary habits |
| title_full_unstemmed | Lateral facet growth of ice and snow – Part 1: Observations and applications to secondary habits |
| title_short | Lateral facet growth of ice and snow – Part 1: Observations and applications to secondary habits |
| title_sort | lateral facet growth of ice and snow part 1 observations and applications to secondary habits |
| url | https://www.atmos-chem-phys.net/19/15285/2019/acp-19-15285-2019.pdf |
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