Fire Rainbow over California

This is a very rare photo of a Fire Rainbow, which was taken in California over the weekend.

For this rainbow to appear, a number of different variables have to align perfectly. Ice crystals must form in wispy, high-altitude cirrus clouds. These crystals then act like thousands of tiny prisms, the same way that raindrops do in a normal rainbow.

These hexagonal crystals must then line up exactly with the sun, which must be very high in the sky (at least 58 degrees above the horizon). As sunlight streams through the cloud at the right angle, the crystals refract the light and create an array of colors.