Quadruple rainbow photographed in Orkney

Quadruple rainbow in OrkneyImage copyright Martin Gray

A rare quadruple rainbow has been photographed in Orkney.

A visible second rainbow is often seen, but the fainter third and fourth arcs due to the bending of light through water in the air are created in a different part of the sky.

The image was captured by Martin Gray at Gyran on Tuesday morning, who described the sight as “amazing”.

He said: “I’m used to seeing double rainbows, but this was a really weird-looking thing.”

“It was Donna, my partner, who saw the rainbow,” he said. “She called me through, but I was on my phone looking at Twitter. When she called me again with real urgency in her voice, I rushed through and there it was – so bright and dominant in the sky.

“I quickly snapped a few photos. It was extremely bright, and odd looking – all odd angles.

“But I didn’t even notice the faint fourth arc until I carefully looked at my photographs.”

Further bounces

The tertiary and quaternary rainbows are far fainter than the more familiar single and double sights.

What forms a normal rainbow is the collective action of rays of sunlight bending through raindrops; the constituent colours of the white light are slightly separated in the process because they travel at slightly different speeds in water.

Much of that bent and separated light then exits the drops, appearing for a given observation point to focus in an arc opposite the sun.

Some of the light takes another bounce within the drop, being bent at a different angle as it passes, creating the second rainbow.

Even smaller proportions make a third and a fourth bounce, and exit in a direction close to the source of the incoming light.

The rainbows that these bounces produce are the faint tertiary and quaternary arcs.

Image copyrighted.