What's A Fire Rainbow? Rare Weather Phenomenon Observed In New Jersey [Photos]

People of New Jersey experienced a rare weather phenomenon called a “fire rainbow” Sunday, which only looked like an oddly shaped-rainbow but was far from it.

Most of the people who took pictures of the unusual phenomenon and posted them on Twitter did so from a beach in Avalon, Cape May County. The photos showed a thin, layered cloud with the colors of a rainbow – red, orange, yellow, green, blue, indigo and violet – arranged in order in the middle.

Adam Joseph, a meteorologist with ABC6 Action News, also posted a photo of the rare phenomenon on his Facebook page, along with a long caption, explaining the phenomenon to those who had never seen it before.

“These are neither fire, nor rainbows. Technically they are known as circumhorizontal arc, an ice halo formed by hexagonal, plate-shaped ice crystals in high level cirrus clouds. The halo is so large that the arc appears parallel to the horizon, hence the name,” the caption read.

It added: “They mostly [occur] during the summer and only in particular latitudes. When the sun is very high in the sky, sunlight entering flat, hexagon shaped ice crystals gets split into individual colors just like in a prism. The conditions required to form a ‘fire rainbow’ is very precise, the sun has to be at an elevation of 58 degrees or greater, there must be high altitude cirrus clouds with plate-shaped ice crystals, and sunlight has to enter the ice crystals at a specific angle. With this said, if you saw this, I hope you enjoyed this rare show in the sky.”

According to IFL Science, Cirrus clouds are the thin, wispy clouds that occur at higher altitudes. A low temperature is imperative for the existence of these clouds as they are made of ice crystals. At the right elevation and angle, the sunlight refracts through the plate-like crystals, which act like prisms and create the colors of a rainbow on the clouds.

Earlier this month, a fire rainbow was observed in parts of New York:

National Weather Service meteorologist Dean Iovino told NJ.com about another rare weather phenomenon, known as “sun dogs,” in which the sun hits ice crystals in high clouds, a process similar to the fire rainbow. “When you are looking up in the sky, you see a bright area that is a reflection,” Iovino said. “In this case [a fire rainbow] you have a little color to it.”

Apart from circumhorizontal arcs, the right combination of the sun and the cirrus clouds can also create other kinds of optical illusions that resemble rainbows, such as cloud iridescence (a diffraction phenomenon caused by small ice crystals individually scattering sunlight), infralateral arcs (formed when sun light enters horizontally oriented, rod-shaped hexagonal ice crystals through a hexagonal base and exits through one of the prism sides), and circumzenithal arcs (located at a considerable distance above the sun, they usually form a quarter of a circle centered on the zenith).