A Brocken spectre is a visual effect in cloud or mist where a person sees their shadow with colored concentric rings centered around the head.
It occurs at high elevations like mountain peaks when sun directly behind an observer casts their shadow on cloud or mist below. The colored rings, called a glory, arise from backscattering of sunlight that has undergone multiple internal reflections within tiny water droplets in the cloud.
It was called a spectre because optical illusions often make the shadow appear oversized. The name Brocken comes from the highest peak in Germany’s Harz mountains, one of the places where the phenomenon has previously been observed.