Atmospheric
Optics
Fogbow, Supernumeraries & Moon, Russia
Sergei Antipov saw this early morning scene at his village some 100km from Nizhny Novgorod.
"The temperature dropped to -1C overnight and had risen to 2C by 06:50 when the sun was bright and I saw this intense fogbow. Inside the primary arc the first supernumerary was visible. I ran indoors to get the camera and a second supernumerary was visible in its LCD viewfinder.
I always use a polarizing filter on the lens and so the rainbow in my picture has maximum brightness over only a part of its arc. In reality, the fogbow was complete.
The memory of my first fogbow is preserved in the photographs."
Note the diminutive Moon. Fogbows like rainbows are huge. Unlike rainbows they can be very broad.
All images ©Sergei Aleksandrovich Antipov
Fogbows are best when the fog/mist layer is thin and a bright sun shines through.
Right: A colour subtraction enhancement reveals 3 to 4 supernumeraries.
So many of them says that the mist droplets had a uniform size. The fogbow spacing changes with droplet size and a mixture of different sizes therefore gives blurred and indistinct supernumeraries.
The faintness of the bow at right is a consequence of the polarizing filter. Fogbows (and rainbows) are strongly polarized. A filter enhances supernumeraries but at a cost of making only part of the bow visible in any single image.
