Rainbow: Fire Rainbows
One of the rarest occurring natural phenomenons.
For this to occur the sun has to be very high in the sky and the cirrus cloud (thin, wispy clouds) has to contain plate shaped ice crystals. The suns rays have to hit the cloud exactly at a 58˚ angle from where the observer stands. It usually happens in areas of higher latitude around the summer solstice.
If the sky is totally covered by cirrus cloud then a halo occurs and other variations such as the kern arc and circumzenithal arc which also require the same varying conditions to become visible.