Fogbow Over Northern Illinois

March 16, 2018

Fogbow 2

Photographer: Lorraine Matti
Summary Authors: Lorraine Matti; Jim Foster

We had really dense fog in northern Illinois on the night of January 21 (2018), so I decided to have some fun and made the panoramic image above with the aid of the headlights on my Jeep. This lovely fogbow, accented by an oak tree and a pile of snow, results from diffraction of light (in this case headlights positioned at the antisolar point) in the minute water droplets composing the fog. Since diffraction, and not refraction, is the dominant scattering process, the bow is broader than a rainbow and nearly devoid of color. However, because the illuminating source here is quite bright and because evidently not all of the droplets are tiny, tints of color can be detected along the bow's outer edge.

Photo Details: Canon EOS 7D camera; 10 mm lens; ISO 800; 0.6 seconds exposure; 4 images stitched together in order to capture the entire bow. Software: Adobe Photoshop CC 2017 (Windows).