Brocken spectre

The optical illusion, pictured at dawn in the Tatra mountains, is actually what is known as a 'Broken spectre', a phenomenon which occurs when there's a low sun shining behind someone looking downwards into fog from a ridge with their shadow projected forwards.

The illusion can appear on any misty mountainside or cloud bank, or even on some occasions, from an aeroplane.

The extraordinary sight involves the light behind a climber casting their shadow often in an odd triangular shape.

The shadow can also fall on water droplets of varying differences from the observer's eye causing confused depth perception.

Amazingly, the ghostly figure can sometimes appear to move rapidly when the cloud layer moves or there are variations in its density.

The head of the figure is often surrounded by rings of coloured light - caused by light diffraction.

The Brocken spectre got its name because of early sightings on the Brocken, the highest peak of Germany's Harz Mountains.

German scientist Johann Silberschlag first observed the phenomenon in 1780 but since then they have been seen and recorded many times in the region.

Among mountain climbers though there is a superstition that whoever sees a Brocken spectre will die in the mountains the very next day.