What are Fogbows?

Fogbows are sometimes called white rainbows or ghost rainbows. They are a rainbow’s colourless cousins, made by a similar phenomenon, but with the small water droplets inside a fog instead of larger raindrops. 

A fogbow is formed from sunlight interacting with water droplets contained in fog, mist or cloud rather than interacting with raindrops as it does in a classical rainbow. Since the water droplets in fog are so small, fogbows have only weak colours or are colourless. 

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, always opposite the sun. Look for fogbows in a thin fog, when the sun is bright. You might see one when the sun breaks through a fog. Or watch for fogbows over the ocean.