A shadowy figure like the Brocken spectre belongs to the group of atmospheric optics. This effect is in fact an optic illusion: when clouds are relative close or surround the observer, its own shadow is projected forward in the mist and the human brain has difficulties to estimate the exact distance. The shadow is exaggerated in dimensions and sometimes it even seems to move when density of mist changes. This ghost like effect has been firstly reported on mount "Brocken" which is part of the mountainous area "Harz" in Germany.  

An artificial Brocken spectre has been created by a pair car lights in foggy conditions: on the right side a double shadow (= two lights) of myself is forwarded at an infinite distance in the fog. All shadow rays are converging to the bright spot around my head which is another optic called "Glory". On the left side part of a "fog bow" is also visible.