Circumzenithal Arc
© Mark HumeMark Hume spotted a circumzenithal arc in North Tyneside.
It may look like an upside down rainbow, but a circumzenithal arc has been spotted in North Tyneside.

Rainbows occur by light refracting off raindrops falling in the sky, but the circumzenithal arc is created by refraction of light from ice crystals.

These crystals are part of cirrus clouds which lie 15,000 - 16,000 kilometers high in the sky.

Unlike normal rainbows, only a quarter of the multi-coloured arc is formed as opposed to a full circle of a rainbow.

Unusual

The circumzenithal arc, or Bravais' arc as it is also known, was spotted in Gosforth on Wednesday 25 August.

Circumzenithal Arc_2
© Mark HumeUn extraño arco iris invertido recientemente observado en el norte de Inglaterra. ¿Sucede algo con la atmósfera?
Although it's not unusual to have high cirrus clouds in summer, as the troposphere is actually higher when it is warmer, it is unusual to spot the arcs as they appear so high in the sky.

So, if you ever see an upside down rainbow, it's not your eyes playing tricks on you, it's our typical weather giving you something to smile about.

If you have some interesting weather pictures, send them to our BBC Look North weather team and you could see your pictures in our monthly galleries.