Unusual rainbow cloud sighting above Ukumehame, Maui

An unusual rainbow cloud formation was captured in video above Ukumehame, Maui on Thursday afternoon.

The video was taken at around 1:30 p.m. on July 7, 2022 of the skies above the Honoapiʻilani Highway in West Maui.

The video shows five linear clouds stacked with each capturing a different color of the spectrum. The area surrounding the rainbow is covered in cirrocumulus clouds.

Photographer Shane Teagarden called the five cloud sky rainbow “an unusual sight.”

An article by EarthSky.org describes the difference between two commonly confused phenomenon: circumhorizon arcs and iridescent clouds. One main difference explained in the publication is that the circumhorizon arc is “well organized” with Red on top and indigo on the bottom, while iridescent clouds are “more randomly distributed.”

Nasa Science notes that a circumhorizon arc is sometimes known as a “fire rainbow for its flame-like appearance.” According to the publication, for this type of event to be visible, “the Sun must be at least 58 degrees high in a sky where cirrus clouds are present. Furthermore, the numerous, flat, hexagonal ice-crystals that compose the cirrus cloud must be aligned horizontally to properly refract sunlight in a collectively similar manner.”

According to the National Oceanic and Atmospheric Administration, rainbow clouds, or cloud iridescence can “usually happens in altocumulus, cirrocumulus, lenticular and cirrus clouds.” According to the NOAA SciJinks website, “iridescent clouds happen because of diffraction – a phenomenon that occurs when small water droplets or small ice crystals scatter the sun’s light.”

The phenomenon, NOAA reports, is relatively rare, as “the cloud must be thin and have lots of water droplets or ice crystals of about the same size.”

“When that happens, the sun’s rays encounter just a few droplets at at time. For this reason, semi-transparent clouds or clouds that are just forming are the ones most likely to have iridescence,” according to the SciJinks website.

*This post was updated after further information was gathered.