This rare optical sight known as “Broken Spectre” occurs when your shadow is cast upon a cloud in opposition to a powerful light source.
The phenomenon is also known as a “mountain spectre” because it most commonly occurs when an observer stands at a higher elevation on a mountain and sees their shadow cast on a cloud at a lower elevation.
A Brocken spectre within glory rings. Image credit: Brocken Inaglory
A Brocken spectre, on the other hand, can appear in any setting when an observer’s magnified (and seemingly enormous) shadow is cast in mid-air against any type of cloud opposite a bright light source.
Furthermore, if the cloud is made up of backscattered water droplets, a glory resembling a saint’s halo can be seen around the observer’s head, caused by the droplets interacting with sunlight or (rarely) moonlight. The glory is composed of one or more concentric, dimmer rings that are always red around the edges and bluish in the center. Because of its appearance, the phenomenon is sometimes mistaken for a circular rainbow, but the latter is much larger in diameter and the result of different physical processes.
The photograph below depicts a Brocken spectre in action (the Sun is behind the observer’s head).
Image credit: Heini Samuelsen
An optical illusion occurs when an observer judges their shadow on relatively nearby clouds to be at the same distance as distant land objects seen through gaps in the clouds, or when there are no reference points to help judge its actual size.
The name comes from a local legend about the Brocken, a peak in Germany’s Harz mountains where frequent fogs and low-altitude access allow it to appear frequently. Giant shadows that seemed to move on their own due to cloud layer movement (which is also a definition of a Brocken spectre) and were surrounded by glories may have contributed to the Harz mountains’ reputation as a land of witches and evil spirits, as reflected in the region’s literature.
The phenomenon can also occur in the vicinity of a plane’s shadow, for example. The center of the glory indicates that the observer was in front of the wings.Image credit: Brocken Inaglory
To include a glory, the clouds or fog responsible for the phenomenon must be located beneath the observer, in a straight line with the Sun’s/position Moon’s in the sky and the observer’s eye.
As a result, as shown above, the glory is frequently seen from a high vantage point, such as a mountain, tall building, or flying aircraft. In the latter case, if the plane is flying low enough for its shadow to be visible on the clouds, the glory always surrounds it. ‘The Glory of the Pilot’ is the name given to this phenomenon.