Approximate Models for Lateral Growth on Ice Crystal Surfaces during Vapor Depositional Growth
Approximate Models for Lateral Growth on Ice Crystal Surfaces during Vapor Depositional Growth
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DOI：
10.1175/jas-d-20-0228.1
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发表时间：
2021-03
影响因子：
3.1
通讯作者：
J. Harrington;G. Pokrifka
中科院分区：
文献类型：
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作者：
J. Harrington;G. Pokrifka
测量结果表明，在小平面上形成冻结的水滴后，这些小平面横向生长在晶体表面上，导致体积和表面积增加，最大尺寸只有很小的增加。这种小平面的横向生长与电容模型和小平面生长理论所预测的明显不同。在本文中，我们开发了两个近似理论的横向增长，一个是经验和一个使用明确的增长机制。我们表明，这两种理论可以重现冻结，过冷水滴的横向增长的整体特征。这两种理论都预测，面积平均沉积系数应随着颗粒的生长而及时降低，这一结果可能有助于解释沉积系数的一些先前测量的分歧。这些理论也可以解释最近在一些测量中发现的近似恒定的质量增长率。我们还表明，经验理论可以重现横向生长时发生的先前升华的晶体再生，可能会发生在冷云中的晶体回收。
Measurements show that after facets form on frozen water droplets, those facets grow laterally across the crystal surface leading to an increase in volume and surface area with only a small increase in maximum dimension. This lateral growth of the facets is distinctly different from that predicted by the capacitance model and by the theory of faceted growth. In this paper we develop two approximate theories of lateral growth, one that is empirical and one that uses explicit growth mechanisms. We show that both theories can reproduce the overall features of lateral growth on a frozen, supercooled water droplet. Both theories predict that the area-average deposition coefficient should decrease in time as the particle grows, and this result may help explain the divergence of some prior measurements of the deposition coefficient. The theories may also explain the approximately constant mass growth rates that have recently been found in some measurements. We also show that the empirical theory can reproduce the lateral growth that occurs when a previously sublimated crystal is regrown, as may happen during the recycling of crystals in cold clouds.