Brocken spectre

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Brocken spectre (also called Brocken bow or mountain spectre) is a large shadow of an observer cast onto cloud or mist, often surrounded by glory rings. This phenomenon occurs when the sun is low and behind the observer, who is looking down from a ridge or peak into mist or cloud.

Formation

The Brocken spectre is named after the Brocken, a peak in the Harz Mountains of Germany, where it was first observed and described. The phenomenon occurs when the sun shines from behind the observer, projecting their shadow onto a cloud or mist bank below. The shadow can appear enormous and distorted due to the perspective and the varying distances of the cloud surface from the observer.

Optical Effects

The Brocken spectre is often accompanied by a glory, which is a series of concentric, rainbow-colored rings surrounding the shadow. This effect is caused by the diffraction of light around water droplets in the cloud or mist. The size and intensity of the glory depend on the size of the water droplets and the angle of the sunlight.

Historical Significance

The Brocken spectre has been a subject of fascination and superstition for centuries. It was first documented by the German scientist Johann Silberschlag in 1780. The phenomenon has been referenced in literature and folklore, often associated with supernatural occurrences due to its eerie and ghostly appearance.

Occurrences

While the Brocken spectre is most commonly associated with the Brocken peak, it can occur in any mountainous region where the conditions are right. It is often observed by climbers, hikers, and pilots who find themselves above a cloud layer with the sun behind them.

Related Phenomena

• Glory (optical phenomenon)
• Fogbow
• Heiligenschein
• Anticrepuscular rays

See Also

• Atmospheric optics
• Light scattering
• Meteorological phenomena