Fire rainbows are beautiful ice halos formed by hexagonal, plate-shaped ice crystals in high level cirrus clouds. Technically called circumhorizontal arcs, they’re an optical phenomenon that occurs when the sun is higher than 58 degrees above the horizon.
They’re very rare, and are only observed when conditions are right. They occur most often during the summer in mid-latitude regions.
Cirrus Clouds
Cirrus clouds are high-altitude clouds that help regulate the amount of heat radiating off Earth. They also help cool the planet by absorbing and scattering incoming sunlight.
When the right conditions are met, water droplets or ice crystals in these clouds can act like prisms to turn sun light into a rainbow. This phenomenon is called a circumhorizontal arc and can happen with altocumulus, cirrocumulus, and lenticular clouds.
For a fire rainbow to form, several variables must be in place. First, the sun must be at least 58 degrees above the horizon and its rays must pass through the cloud at a specific angle.
The light then refracts or bends through the hexagonal plate-shaped ice crystals in these clouds. This bending causes the colors to separate and create the fire rainbow we see.
Sunlight
Sunlight is the light rays of the sun that hit Earth’s surface, giving off visible, ultraviolet (UV), and infrared (IR) radiation.
The rays are scattered throughout the atmosphere by air molecules, which cause clouds to form. This scattering of sunlight allows it to reflect off water droplets in clouds, creating rainbows.
But in some special conditions, this refraction can be used to create a spectacular phenomenon: fire rainbows!
To see a fire rainbow, the Sun must be high in the sky – at least 58 degrees above the horizon. The sky must also contain cirrus clouds with hexagonal plate-shaped ice crystals aligned with flat faces parallel to the ground.
When sunlight enters these ice crystals, it refracts, or bends, at a precise angle to split the colors of the spectrum into individual bands. This process is similar to a prism, but with more intense colors. It happens mostly during summer and in certain latitudes between 55deg North and South of the equator.
Refraction
When sunlight passes through ice crystals that are aligned in specific ways, they can bend the light to create a stunning array of colors. This process is called refraction, and it can also be responsible for natural optical phenomena like mirages.
A fire rainbow occurs when the Sun is high in the sky and the cirrus clouds have hexagonal plate-shaped ice crystals that are aligned with flat faces parallel to the ground. These crystals are capable of bending sunlight at precise angles that separate the color components into their component wavelengths.
Fire rainbows are rare occurrences that can only occur at specific altitudes and during certain times of the year. They are most commonly spotted in the US, but can also be seen from Europe and Asia.
Artificial Fire Rainbows
Fire rainbows are a rare weather phenomenon that happens when the sunlight passes through thin, wispy cirrus clouds and is refracted. The cirrus clouds are made of millions of hexagonal ice crystals that form in the upper levels of the atmosphere.
They form when the sun is high enough in the sky, but the ice crystals in the cloud must be aligned correctly so that the light can be properly refracted and split into different colors. That’s why they’re a rare sight to see.
If you’re ever in a place where you can see this beautiful, shimmering display, take advantage of it! During the summer, you can expect these iridescent arcs to appear over some parts of the US. However, the frequency and duration of occurrence vary widely depending on latitude and weather conditions. it’s very helpful to understand what causes fire rainbows and other aspects of the nature that surrounds us.
