A shocking climate phenomenon was noticed over elements of Virginia this week – a so-called "rainbow cloud," which seems to be like a brilliant prism of colour behind comfortable clouds. A number of individuals in Hamilton, Virginia, despatched in images of phenomenon to WUSA-TV, a CBS affiliate in Washington, D.C.
Whereas many have been calling it a "rainbow cloud," it's extra precisely an atmospheric optic known as cloud iridescence. However what precisely is that?
"Cloud iridescence varieties when the water droplets or ice crystals within the cloud diffract the sunshine across the outdoors of the droplet, versus bending the sunshine by means of it," The Climate Channel meteorologist Jen Carfagno instructed CBS Information.
"The colours of the spectrum aren't as neat and arranged in iridescence as in a rainbow," she added. "Cloud iridescence jogs my memory of pixie mud or unicorn sprinkles."
So-called rainbow clouds are pretty uncommon, stated Carfango, who co-hosts "America's Morning Headquarters." They're typically noticed close to the polar areas, or in mountain areas within the winter. The clouds should be close to the solar.
The clouds have to be very skinny and product of ice crystals or water droplets of uniform dimension. So cloud iridescence often occurs in lenticular or alto-cumulus, cirrus and cirrocumulus clouds.
"Within the case from this week in Northern Virginia, what occurred was that a pileus cloud, AKA a 'cap cloud,' shaped on prime of a late afternoon cumulonimbus cloud," Carfagno stated. "This cover cloud is a standard function on prime of robust thunderstorms."
A rainbow cloud is the same rainbow, halo, sundog, circumhorizontal arc, as a result of it varieties because of the diffraction or refraction of sunshine.
In 2018, a comparable "fireplace rainbow" was noticed in Vermont. This phenomenon, technically known as a circumhorizontal arc, happens when the solar could be very excessive within the sky – greater than 58 levels above the horizon – and its mild is refracted by ice crystals suspended within the ambiance, in line with Nationwide Climate Service (NWS).
This phenomenon seems to be like a really giant halo and is simply seen in cirrus clouds, that are made out of ice crystals and look wispy. When the cirrus clouds are lit with colour, they are often mistaken for iridescence, in line with the NWS.
Rainbow clouds and fireplace rainbows are completely different, and the colours in a hearth rainbow are far more vivid than in a rainbow cloud, Carfagno defined.
Carfagno stated the "rainbow cloud" noticed over Virginia has been described by some as psychedelic in colour, which is an effective description as a result of it offers a clue concerning the cloud sort.
"Cloud iridescence is just not as uniform in colour as is a daily rainbow or a halo or a circumhorizontal arc," she stated.