Heiligenschein and Anticrepuscular Rays
December 29, 2021
Photographer: Marco Meniero
Summary Author: Marco Meniero
On the morning of October 07 2021, I photographed anticrepuscular rays from the control tower of the airport at Viterbo, Italy. These rays, sometimes called antisolar rays, appear opposite of the Sun and converge at the antisolar point. So you must have your back to the Sun in order to see them.
On both the top and bottom photos you can see a rather bright spot or patch of light (at the top of the shadow made by the control tower, where I'm standing with camera in hand) that follows me. When I looked to the right, the spot is seen on the right; when I looked to the left the spot was seen on the left. This spot is termed a Heiligenschein. It can be detected whenever dew drops form on various surfaces. The nearly spherical dew drops act as lenses to focus the light onto the surface behind them. When this light scatters or reflects off that surface, the same lens re-focuses that light into the direction from which it came. This configuration is sometimes called a cat's eye retroreflector. Any retroreflective surface is brightest around the antisolar point.