Virginia bystanders were left mesmerized after they witnessed what some are calling a “rainbow cloud.”
The incredible weather phenomenon appeared to be a bright prism of color peeking behind clouds. Several bystanders were lucky enough to snap some pics of the rare moment in Hamilton, Virginia.
While some called it a “rainbow cloud,” it’s more accurately defined as an atmospheric optic called cloud iridescence. So we’re taking it back to our middle school science class days and diving into what this means.
According to Weather Channel meteorologist Jen Carfagno, “Cloud iridescence forms when the water droplets or ice crystals in the cloud diffract the light around the outside of the droplet, as opposed to bending the light through it.” She added: “The colors of the spectrum are not as neat and organized in iridescence as in a rainbow.”
Carfagno even described the iridescence as looking like “pixie dust” or “unicorn sprinkles.” She also stated that these rainbow clouds are relatively rare. You can often find them near the polar regions or in mountainous areas in the winter. The clouds also need to be near the sun to create this phenomenon.
Meteorologist says ‘Rainbow Cloud’ typically appears on top of thunderstorms
The clouds must also be reasonably thin and made of ice crystals or water droplets of the same size. As a result, cloud iridescence usually happens in alto-cumulus, cirrus, and cirrocumulus clouds.
“In the case from this week in Northern Virginia, what happened was that a pileus cloud, AKA a ‘cap cloud,’ formed on top of a late afternoon cumulonimbus cloud,” Carfagno said. “This cap cloud is a common feature on top of strong thunderstorms.”
Several years ago, in 2018, someone spotted a rare fire rainbow in Vermont. This occurrence, technically called a circumhorizontal arc, occurs when the sun is very high in the sky above the horizon. According to the National Weather Service, its light is refracted by ice crystals suspended in the atmosphere.
This phenomenon presents as an enormous halo and is only visible in cirrus clouds, consisting of ice crystals that appear wispy.
Per reports from the National Weather Service, when the cirrus clouds are lit up with color, they can be mistaken for iridescence. However, it’s important to note that rainbow clouds and fire rainbows are different. Fire rainbows feature their colors in a much more vivid way, compared to a rainbow cloud, Carfagno explained.
Carfagno said the “rainbow cloud” spotted over Virginia has been described by some as psychedelic in color, which is a good description because it gives a clue about the cloud type.
“Cloud iridescence is not as uniform in color as is a regular rainbow or a halo or a circumhorizontal arc,” she said.