What Is A Fogbow Or White Rainbow?
Have you heard of a fogbow? We sure haven't, but it's pretty awesome.
Above is a picture of a fogbow taken September 6, 2019, near Maine, NY. A fogbow is similar to a rainbow but dimmer and not as colorful. Earthsky.org says a fogbow is a rainbows cousin. They're almost as large as a rainbow and much, much broader.
Fogbows – sometimes called white rainbows, cloudbows or ghost rainbows – are made the same as rainbows are, from the same configuration of sunlight and moisture. Rainbows happen when the air is filled with raindrops, and you always see a rainbow in the direction opposite the sun. Fogbows are much the same, still opposite the sun, but fogbows are caused by the small droplets inside a fog or cloud rather than larger raindrops.
Website Atmospheric Optics says the best was to see a fogbow is to look away from the sun and at an angle of 35-40 degrees from your shadow which marks the direction of the antisolar point. Some fogbows have very low contrast so look for small brightenings in the misty background. Once caught, they are unmistakable.