#suncups

Ah . . . suncups.

Suncups are often bowl-shaped (can be more like the above photo) open depressions in a snowfield. They form closely packed, honeycomb, often hexagonal patterns with sharp narrow ridges separating smoothly concave hollows. They can make for very tough walking!

Suncups form during the melting away of snowy surfaces. I often notice them where there is differential melting away of dirty snow. They may occur melting of clean snow by incident solar radiation on bright sunny days.

Landscape Language

Sublimation (noun) – direct transition from a solid to a vapor

Suncups, bowls of snow that form at high elevations on the mountain, are created through sublimation. At lower elevations, snow melts from a solid into liquid water, then may evaporate into water vapor. But at high elevations during the summer, the sun can be intense enough but the air still cold and dry enough that snow can evaporate directly into water vapor without a liquid state. The snow further reflects the sunlight, deepening the bowls and creating large spikes over time, called penitentes. Have you experienced these snow features while climbing the mountain?

PCT hikers face many challenges.  Most they think of well before they begin their journey -- heat, cold, thirst, fatigue, animals, lightning, wind, river crossings, etc.  Suncups rarely if ever come to mind.  Admittedly, they probably should fall in the same category as mosquitoes or mice, but should you encounter a broad snow field of extreme suncups they will quickly become indelibly etched in your memory.  They make for exhausting walking!

Suncups are bowl-shaped open depressions in the surface of a snowfield.  Although they are normally wider than they are deep, they can become almost diabolically steep and packed together. They form honeycomb, often hexagonal patterns with sharp narrow ridges separating smoothly concave hollows.  The suncups on most patches of PCT snow are benign but not always (see above and below).

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