Melting on the sun...

Bruno - Jan 9, 2008 10:49 am - Hasn't voted

I don't know whether there is a special name for it in Tibetan, but the English terms derivates from Spanish: "Penitent Ice" or Penitent snow".

Unlike in the Andes, I haven't seen here in Tibet large fields of penitents on snow fields (typically 0.5 to 2m tall), but only on glacier where there are much larger (typically 2 to 10m) but also not so close to each other. However, the process of formation is the same: sublimation of ice into vapor under very strong insulation and dry air. There is a good online definition in the glossary of meteorology:

Penitent ice or penitent snow: A spike or pillar of compacted snow, firn, or glacier ice caused by differential melting and evaporation. Necessary for this formation are 1) air temperature near freezing; 2) dewpoint much below freezing; and 3) strong insolation. Consequently, penitent ice is most developed on low-latitude mountains, especially the Chilean Andes, but has been found in polar regions. Penitents are oriented individually toward the noonday sun, and usually occur in east–west lines. The term is derived from the Spanish nieve penitente (penitent snow), which is still widely used throughout the literature.