PENINTENTES

Combine snow, cold temperatures, bright sunshine, wind and very dry air often snow does not melt, but directly sublimates (converts from solid directly into gas form). If the conditions are correct bowl shaped structures will form where the snow sublimates in the cavity, but not as quickly on the raised portions between the bowls. The sublimation is greatest at the bottom of any cavity and least on the peaks and sides. This process will at first scallop the surface of the snow, then as the bowls get deeper peaks and ridges form, the cavities growing downwards through the snow pack. The resulting structures appear as tall pillars of snow with deep cavities between them.

These odd structures really catch the attention, so much so I became curious and researched the mechanism behind their formation and whatever else I could find out about these strange formations. Interestingly they are first described in the scientific literature by Charles Darwin who encountered penitentes near the Piuquenes Pass in the Andes Mountains. Called 'snow cups' or 'penitentes' due to their resemblance to pilgrims or hooded religious figures the results can be startling in their strangeness. The pillars can be taller than a person, but the tallest I have seen on Mauna Kea this winter are about one meter, mostly just half a meter, I suspect they could be taller if given a chance, but that is the depth of the remaining snow fields. The conditions for forming penitentes have been present at the summit for the last couple months, and the process has been carving at the deeper remaining snow fields on the tops of the ridges and north sides of the pu'us at the summit. Currently entire snow fields of acres in size are carved deeply with these penitentes in the summit area. This has resulted in entire gardens of penitentes along the roads at the summit and another reason why the summit continues to be such a beautiful and fascinating place.