Brocken Spectre and Glory 1/6/2007 near Yarra Glen, Melbourne, Victoria, Australia.
© Copyright Ern Mainka
Brocken Spectre and Glory
….The Brocken Spectre is the three dimensional shadow at the centre. It is dark air extending from the person/photographer all the way into the distance. Brocken shadows look triangular and large because of this.
….Glories (similar looking to a rainbow) form by diffraction, reflection and refraction of sunlight through water/mist droplets. Their formation involves surface waves as well as internal reflections. The number of rings and their angular extent is a function of the size distribution of the water droplets that compose clouds. With larger droplets the rings are more tightly packed. The clearer the colors appear in the fringes, the tighter the size distribution of the droplets (closer to one single size). Glories are polarized radially in the outer color fringes but tangentially in the center.
A Brocken spectre (German Brockengespenst), also called Brocken bow or mountain spectre is the apparently enormously magnified shadow of an observer, when the Sun is low, cast upon the upper surfaces of clouds. If the observer is in an aeroplane, the shadow of the aeroplane is cast. The phenomenon can appear on any misty mountainside or cloud bank, but the frequent fogs and low-altitude accessibility of the Brocken, a peak in the Harz Mountains in Germany, have created a local legend. The 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 same distance as faraway land objects seen through gaps in the clouds. The shadow also falls on water droplets of varying distances from the eye, confusing depth perception. The ghost can appear to move (sometimes quite suddenly) because of the movement of the cloud layer. The head of the figure is often surrounded by the glowing halo-like rings of a glory (Heiligenschein), rings of coloured light that appear directly opposite the sun when sunlight is reflected by a cloud of uniformly-sized water droplets.