Brocken's spectrum, a mysterious optical phenomenon visible in the mountains

Definition and origin of the name

The Brocken Spectrum is named after Brocken, the highest peak in Germany's Harz Mountains, where the phenomenon has been frequently observed and described. The term “Brocken” refers to this specific location, but the phenomenon itself can occur on any mountain or ridge.


Description of the phenomenon

The Brocken Spectrum occurs when an observer's shadow is cast on a cloud or fog bank below the observer's position. The shadow appears gigantic and can sometimes be surrounded by colored rings called “glories”.


Formation conditions

For the Brocken Spectrum to appear, several conditions must be met:

- Observer's position: The observer must be high up on a mountain or ridge.
- Light source: The sun must be low in the sky, usually near the horizon, either at sunrise or sunset.
- Fog or clouds: There must be a bank of fog or clouds below the observer.
- Angle of View: The shadow must be cast towards the fog or clouds, so that the observer is looking away from the sun.

Scientific explanation

The phenomenon occurs due to the scattering of light. Water droplets in fog or clouds act like thousands of tiny prisms, refracting, reflecting and scattering sunlight. When the observer's shadow is cast on these droplets, it can appear disproportionately large, sometimes surrounded by colored rings due to light interference.

Visual appearance

- Enlarged Shadow: The observer's shadow can appear huge and somewhat distorted due to perspective and distance.
- Glories: The colored rings around the shadow, similar to concentric rainbows, are caused by the diffraction of light by water droplets. These glories often appear in several brightly coloured circles.

Cultural and historical aspects

Brocken's Ghost has been documented and evoked in many cultures and mountain stories. It has often been interpreted as a mystical or supernatural sign by mountaineers and travelers who did not understand the mechanisms behind the phenomenon.


Experiences and testimonials

Many hikers and mountaineers have reported spectacular experiences of seeing their own Brocken spectre. The experience is often described as both astonishing and somewhat frightening, due to the imposing appearance of the shadow and the mystical aura of the glories.


The Brocken Specter remains one of the most fascinating and mysterious optical phenomena one can witness in the mountains. Its unique combination of science and natural spectacle captivates hikers and mountaineers, offering a rare and fleeting glimpse of the magic of light. Whether you're a fan of natural phenomena or an avid hiker, witnessing this spectacle is an unforgettable experience. So, the next time you find yourself on a mountain ridge with the sun low on the horizon and a bank of fog below, get ready to be amazed by your very own Brocken Specter.