'Upside down rainbow' caused by freak weather

Freak atmospheric conditions rarely seen outside the polar regions have been credited with causing the formation of an "upside down rainbow".

Normal rainbows are made when light penetrates raindrops and re-emerges out the other side in the same direction but the inverted types, known as circumzenithal arcs, are caused when sunlight bounces off ice crystals high in the atmosphere, sending the light rays back up.