cloudbow

A cloudbow, also known as a fogbow or cloud rainbow, is an optical phenomenon similar to a rainbow but formed by light refracted through water droplets suspended in the atmosphere within clouds or thick fog. Unlike traditional rainbows, which require sunlight to pass through rain droplets at a specific angle, cloudbows appear when sunlight interacts with much smaller water droplets in mist or low-lying clouds. This interaction scatters light diffusely, resulting in a faint, pastel-colored arc that lacks the vivid hues of a rainbow.

Cloudbows often appear as white or lightly colored arcs, sometimes with subtle hints of blue or green, due to the limited scattering of light within the droplets. They typically form in regions where sunlight is partially obscured by clouds, such as near the horizon or in areas of dense fog. Unlike rainbows, which are caused by refraction and reflection inside larger droplets, cloudbows rely on Mie scattering, where light interacts with particles of a similar size to its wavelength.

The phenomenon is most noticeable when the sun is low in the sky, creating a broad, diffuse arc that can stretch across the sky. Cloudbows are frequently observed in coastal areas, mountainous regions, or during early morning or late evening when atmospheric conditions favor the presence of fine water droplets. Unlike rainbows, which are often associated with rain showers, cloudbows do not require precipitation and can occur in stable, humid conditions.

While cloudbows share the same basic principles as rainbows, their appearance is subtler and less vivid, making them a less commonly discussed but equally fascinating atmospheric display. They serve as a reminder of the intricate ways light interacts with the natural world.