A Brocken spectre (German Brockengespenst), also called Brocken
bow or mountain spectre is the apparently enormously magnified
shadow of an observer, cast upon the upper surfaces of clouds
opposite the sun. The phenomenon can appear on any misty
mountainside or cloud bank, or even from an aeroplane, but the
frequent fogs and low-altitude accessibility of the Brocken, a
peak in the Harz Mountains in Germany, have created a local
legend from which the phenomenon draws its name. The Brocken
spectre was observed and described by Johann Silberschlag in
1780, and has since been recorded often in literature about the
region. The "spectre" appears when the sun shines from behind a
climber who is looking down from a ridge or peak into mist. The
light projects the climber's shadow forward through the mist,
often in an odd triangular shape due to perspective. The
apparent magnification of size of the shadow is an optical
illusion that occurs when the observer judges his shadow on
relatively nearby clouds to be at the sa