Penitentes 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 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) and range in length from a few centimeters to over 5 meters (16 ft).