GONZALES – Storm Station viewer Ami Barden spotted a colorless half circle, or bow, across the horizon in Gonzales on Wednesday morning. It was not a gray rainbow. In fact it had not rained all night. However, there was fog. This was what is known as a fogbow.

A fogbow forms very much like a rainbow as sunlight interacts with water droplets. The drops found in fog are 10 to 1000 times smaller than in rain, only about 0.1 millimeters in diameter.

Just like in a rainbow, the observer has sunlight behind and water droplets in front. The key difference with a fogbow is the visual process at work. A rainbow is formed via refraction—that is when light passing from air through a more dense raindrop, it disperses and changes color. A fogbow is formed via diffraction—that is when the light broadens through the droplet and blurs the colors causing it to appear white. This is also why a fogbow appears much brighter than a rainbow.

The fog has to be fairly thin and diffused in order for a fogbow to appear. Sometimes, multiple pale colored rings called a glory will appear at the center of a fogbow.

When you see weather happening, share it with us! Email photos to weather@wbrz.com or submit them via the Storm Station Weather App.