Lunar Fogbow Observed in Saxony, Germany

January 01, 2021


Photographer: Heiko Ulbricht 
Summary Authors: Heiko Ulbricht; Jim Foster

For the first time in my life I saw a lunar fogbow, as pictured above arching over an agricultural field in Grumbach, Germany. Because the Moon was full, this fogbow, also called a cloudbow, was easily visible.

Droplets that form fogbows are only about 1/10 the diameter of the raindrops that form rainbows. As a result, there’s greater wave interference since the wavelengths of visible light tend to overlap within the tiny droplets. This leads to bows that are not only wan in appearance but are somewhat wider than rainbows. Photo taken on October 31, 2020. Note that as this happened to be a Blue Moon, being able to observe this fogbow was a bit more special.

Photo Details: Canon EOS 6D camera; Sigma ART 24 mm; F2.8; 30-second exposure; ISO 400