penitents

The abbreviated way of referring to penitent snows. This name is given to the striking pinnacles of compact snow, of highly variable height (from a few centimeters up to between 4 and 5 meters), into which a snow cover subjected to very particular and extreme meteorological conditions ends up being transformed. Such a curious name is due to the resemblance they bear to a procession of penitents in Holy Week, each of them dressed in their pointed hood. They have been documented in high mountain areas of different mountain ranges around the world, being most frequently formed in the desert, mountainous region of the Central Andes of Argentina and Chile, usually above 4000 m above sea level. In Spain, they occasionally form both in the Pyrenees and on Mount Teide. These ice needles are the result of the loss of snow through melting and sublimation. In the aforementioned Andean area, the environment, apart from being icy, is so extremely dry that surface snow begins to evaporate, forming concavities in the snowpack. As those gaps gradually enlarge, the solar factor becomes relevant (differing insolation between sunny and shaded areas), which accelerates the process of snow loss, progressively perforating the layer until culminating in the formation of that kind of ice stalagmites. The first scientific reference to penitentes is due to the English naturalist Charles Darwin (1809-1882), who came across them on an expedition through the Andean region, on March 22, 1835. The French glaciologist, based in Chile, Louis Lliboutry (1922-2007) was the first to satisfactorily explain how they form.