Also: Temperature-Gradient metamorphism, TG, Facets, Angular Grains, Depth Hoar, etc
Crystal growth or metamorphism which occurs at a very fast (much greater than equilibrium) rate due to a large temperature gradient or other strong non-equilibrium factors. Grains become faceted and bond poorly. [Colloquially called "sugar snow" sometimes.]
In the advanced stages the crystals are layered, scrolled, cupped and often hollow. [Colloquially "Advanced TG" or "Depth Hoar"]
A layer of these facets often forms early in the season if a thin snowcover sits on the ground under steep temperature gradients for while. This layer often reaches the advanced stages and is subsequently buried. "Depth hoar" usually refers to this bottom layer.
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