Suncup (snow)

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Suncups on a snow patch near Gibby Beam, UK.

Suncups are bowl-shaped open depressions into a snow surface, normally wider than they are deep. They form closely packed, honeycomb, often hexagonal patterns with sharp narrow ridges separating smoothly concave hollows. For a given set of suncups, the hollows are normally all around the same size, meaning that the pattern is quasi-periodic on 20–80 cm scales.[1][2] The depressions are typically 2–50 cm deep.[3]

Suncups form during the ablation (melting away) of snowy surfaces. It is thought they can form in a number of different ways. These include melting of clean snow by incident solar radiation in bright sunny conditions,[3] but also during melting away of dirty snow under windy or overcast conditions, during which particles in the snow accumulate on the crests between hollows, insulating them.[4]

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  1. ^ Post, A., and LaChapelle, E.R. 1971. Glacier ice. Seattle and London, University of Washington Press.
  2. ^ Herzfeld, Ute C., et al. "Morphogenesis of typical winter and summer snow surface patterns in a continental alpine environment." Hydrological processes 17.3 (2003): 619-649.
  3. ^ a b Rhodes, Jonathon J., and Stephen G. Warren. "MODE OF FORMATION OF ABLATION HOLLOWS CONTROLLED BY DIRT CONTENT OF SNOW." Journal of Glaciology 33.114 (1987).
  4. ^ Betterton, M. D. "Theory of structure formation in snowfields motivated by penitentes, suncups, and dirt cones." Physical Review E 63.5 (2001): 056129.