Due to weak lighting conditions and water droplets that are much smaller than raindrops, fogbows and moonbows are often seen only in silver-white hues.
The phenomenon of a moonbow.
Rainbows are a phenomenon of sunlight dispersion when refracted and reflected through raindrops.
While it is often said that rainbows appear after it rains, this is true but not always accurate in many cases. Specifically, fogbows appear due to thin mist in conditions of sudden cold air.
According to Earth Sky, this phenomenon is created by sunlight and extremely small water droplets, with diameters less than 0.05 mm. Because they are so small, these droplets cannot refract light to create the multi-colored effect seen with raindrops.
Additionally, the phenomenon of moonbows also appear in a single color. Unlike fogbows, this phenomenon is caused by moonlight, not sunlight.
Moonbows occur when moonlight is refracted by water droplets suspended in the air, such as during rain showers or from waterfalls. This phenomenon is very difficult to observe with the naked eye; only long-exposure photography can reveal the full spectrum of colors in a moonbow.
