A free-standing column of ice, firn, or compacted snow that has been formed by differential melting and sublimation. Small, initial depressions collect dust, which absorbs radiation efficiently in summer, causing the ice at the bottom of the hollows to melt, whereas clean ice at the peaks sublimes. Melting requires far less energy (about one-eighth) of that required for sublimation, so the hollows deepen more rapidly than the peaks, eventually reaching the ground and producing separate columns of ice. Frequently known by the Spanish term nieve penitente (‘penitent snow’).
Subjects: Meteorology and Climatology.