
Rare: The specific angle means the phenomenon, seen in West Yorkshire, is most common at middle latitudes, like the southern US
Because such a specific angle is necessary for the colours to be visible, the phenomenon is most common at middle latitudes, which includes the southern United States. Sightings of the arcs in Europe are much rarer.
The phenomenon was first dubbed a 'fire rainbow' back in 2006, when one was spotted by a Washington journalist and a strict set of conditions are required for such a thing appear in the sky.
Cloud iridescence only occur in high-level cirrus clouds, which usually form about 18,000ft. They appear thin and wispy and are made up of tiny ice crystals.
To produce the rainbow colours the sun's rays must enter the ice crystals at a precise angle to give the prism effect of the colour spectrum.
The sun must also be at an altitude of at least 58 degrees above the horizon.
Natural phenomenon: The 'fire rainbow' clouds appeared to have a more red-orange hue in the pictures taken in Cumbria
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