Beautiful pictures and a video have emerged of an ‘upside down’ rainbow in skies above East Lancashire – but what causes this phenomenon?
Kush Yusuf managed to take pictures of the rainbow, which was first spotted by his daughter, Ammarah.
He said: "I have spotted an upside-down rainbow in Blackburn and took some pictures and a video.
“My three-year-old spotted it first and we were amazed at the sight.
“I managed to take a few pictures and after about 10 minutes it faded away. Never seen anything like it. It was amazing.”
According to the Met Office what we are actually seeing is a circumzenithal arc, sometimes known as Bravais' arc, which is an optical effect
This is formed formed when sunlight refracts through horizontal ice crystals at such an angle which causes the distinctive upside-down rainbow effect.
They are commonly associated with Cirrus clouds (short, detached, hair-like clouds found at high altitudes) where ice crystals readily form.
Circumzenithal arcs are quite common and can occur at any time of the year.
However, they can be hard to spot as they are usually obscured by clouds underneath
In order to be able to see a circumzenithal arc, a combination of atmospheric conditions must coincide.
The height, depth and position of the ice clouds must be right as the cloud needs to be at a specific angle to the sun.
The position of the observer is also important since its visibility can vary greatly over short distances.
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