July - lightning You are here: Home Photo gallery Atmospheric optics Light in water droplets Brocken spectre


The Brocken spectre is named after a region in Germany where the phenomenon is observed frequently. The Brocken spectre is your shadow projected onto and in a cloud, like fog. Due to perspective misleading you in estimating dimensions, the shadow will look much bigger than you are. You see a distant figure in the fog, about at the distance where the fog becomes opaque. If the light source (the sun, usually) is far away, that figure is as tall as you are. However, because all the shadow parts are rays emerging from you into that distant shadow figure, it looks as if the distant figure does not decrease in angular extend with distance as much as perspective would suggest, and hence looks bigger. Also, denser and less dense parts of the cloud may move by, changing the optical thickness and causing the shadow to move. This gives the spectre its startling and ghostlike appearance.

2 photos in gallery
Click images for large photos




w-375-36

w-374-12