On a quiet afternoon in Massachusetts, the sky erupted in an explosion of fire and colour. Spectators craned their necks, their jaws slack, as waves of neon red, electric blue, and searing gold rippled across the heavens. Some gasped. Others fumbled for their phones, desperate to capture the moment before it vanished. It looked like a supernatural portal had cracked open above them. But what was this otherworldly display? A message from beyond? A celestial omen? Or just an optical illusion so rare it defies belief?
Scientists have a name for this baffling spectacle: the circumhorizontal arc. The world, however, knows it by a far more dramatic title—the fire rainbow. But don’t be fooled. It’s neither made of fire nor an actual rainbow. And yet, it’s one of the most breathtaking natural illusions to ever set the sky ablaze.
What Exactly Is a Fire Rainbow?
If you think fire rainbows are just another version of a traditional rainbow, you’re dead wrong. Unlike rainbows, which form when light refracts through raindrops, fire rainbows emerge when sunlight passes through ice crystals high in the atmosphere. These crystals, suspended within delicate cirrus clouds, act like microscopic prisms, bending and scattering light into an explosion of vibrant hues. But here’s the catch: this phenomenon only happens when very specific conditions align.
For a fire rainbow to ignite the sky, the Sun must be at least 58 degrees above the horizon. If it’s too low, the light can’t hit the ice crystals at the perfect angle. That’s why these sky fires are almost impossible to see in places above 55 degrees latitude, like northern Europe or Canada.
Even in areas where they can occur, they remain incredibly elusive. The perfect mix of high-altitude cirrus clouds and the right Sun position must happen at the exact moment. Miss it by a few minutes? Too bad. You’ll be left staring at a regular, unimpressive sky while someone else captures a viral masterpiece.
A Rare Cosmic Firestorm
Despite their rarity, fire rainbows have been spotted across the United States multiple times in recent years. Just this year, residents of Newburyport, Massachusetts, were left spellbound when a fire rainbow appeared through a gap in the cloud cover. It was like nature had carefully placed an ethereal painting in the sky for all to see.
Earlier, in April 2024, another dazzling fire rainbow was recorded over Oak Harbor, Ohio. Videos spread across social media, sparking wild theories. Some speculated it was a government experiment. Others, a warning from the cosmos. The truth? Just another fleeting moment of optical perfection—a trick of light, ice, and physics.
The Science Behind the Magic
The reason fire rainbows appear so electrically vibrant is due to the way hexagonal ice crystals refract sunlight. These crystals must be aligned horizontally within the cirrus clouds. If they are tilted even slightly, the refraction effect is lost, and the spectacle disappears. Essentially, the entire cloud acts as a gigantic prism, scattering sunlight into its full spectrum.
This also explains why fire rainbows always appear parallel to the horizon—a stark contrast to traditional rainbows, which arc across the sky. And unlike cloud iridescence, which causes random swirls of colour, fire rainbows are structured, with a clear red-to-violet sequence.
Are Fire Rainbows an Omen?
Every time a fire rainbow appears, conspiracy theories explode. Some believe it’s a harbinger of disaster, a cosmic warning that something big is coming. Others swear it’s a portal to another dimension, a rupture in the sky revealing the secrets of the universe. Of course, scientists dismiss these ideas, waving them off as nothing more than wishful thinking. But still—why do fire rainbows feel so… supernatural?
Perhaps it’s because they’re so rare and fleeting. They appear suddenly, like a celestial mirage, and then they’re gone. Unlike the predictable arc of a regular rainbow, fire rainbows are chaotic, untamed, and seemingly impossible. Maybe that’s why they captivate us so much.
