The Atacama desert is known by meteorite hunters to be very cold and very dry.
These harsch weather conditions allow natural ice spikes – known as penitentes – to form and make the landscape look decidedly alien.
The penitentes (Spanish for penitents) are a curious natural phenomenon found in high altitude regions, typically more than 4000 metres above sea level where it’s very cold and very dry.
They are thin spikes of hardened snow or ice, with their blades pointing towards the Sun, attaining heights from a few centimetres up to several metres.
How do penitentes form in the desert?
Many people have heard of the Atacama desert. It is so dry in places that footprints in the dust stay undisturbed for decades. And this very dry climate is responsible for the formation of these giant ice needles!
The snow undergoes a process of sublimation – when ice changes directly to gas without changing to water first. The sublimation causes pits in snow that hollow out to deeper caverns. When ice sublimates in the caverns, it turns to mist – and makes the climate in the cavern wet enough for liquid to form.
The combination of melting and sublimation sculpts elaborate ice figures, which look even cooler next to a telescope.