What are nieves penitentes?

Penitentes, or nieves penitentes (Spanish for "penitent-shaped snows"), are snow formations found at high altitudes. They take the form of elongated, thin blades of hardened snow or ice, closely spaced and pointing towards the general direction of the sun.

The name comes from the resemblance of a field of penitentes to a crowd of kneeling people doing penance. The formation evokes the tall, pointed habits and hoods worn by brothers of religious orders in the Processions of Penance during Spanish Holy Week. In particular, the brothers' hats are tall, narrow, and white, with a pointed top.

These spires of snow and ice grow over all glaciated and snow-covered areas in the Dry Andes above 4,000 metres (13,000 ft). They range in length from a few centimetres to over 5 metres (16 ft).