Snow can get funny at high altitudes and on mountains. It can be powdery soft, squeeky and crunchy, wet and gummy, or even form strange shapes depending on pressure, humidity, temperature, and a host of other conditions. It’s one of the fascinating parts I love about climbing mountains.

In the high Atacama desert, 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).

Penitentes up to 15 metres (49 ft) high are suggested to be present in the tropics zone on Europa, a satellite of Jupiter. According to a recent study, NASA’s New Horizons has discovered penitentes on Pluto, in a region informally named Tartarus Dorsa