Elusive ‘fog rainbow’ captured on camera near San Francisco: ‘Breathtaking’

The phenomena are sometimes caled “white rainbows” or “ghost rainbows”

When light shines through the prism of water in a raincloud, it can form a rainbow that illuminates each distinct hue of visible light. But when that light shines through the prism of water in some fog, it can form a “fogbow.”

One San Francisco man recently got a glimpse of this phenomenon in the Marin Headlands just north of the Golden Gate bridge.

“It was breathtaking,” Stuart Berman told SFGate this week. “I could not stop staring at it.”

Mr Berman was on a hike with a friend when they saw the streaks of light in the early morning fog, he told the publication.

He snapped a photo of the formation, which he said was about 75 – 100 yards (69 – 91 metres) wide and posted it on Twitter.

“Yesterday morning, I went for a walk in the Marin Headlands and saw a sight unlike any I’d seen before,” Mr Berman tweeted.

The photo shows concentric haloes of light streaming through the misty air above the shrubby landscape, fog still obscuring the blue sky in the background.

Fog rainbows form similarly to rainbows as light passes through water — but the water droplets in fog are much smaller than rain, which can change the effect, according to the UK’s meteorological office.

Since the droplets are smaller, the diffused light can appear much more diffuse and paler in colour than a more traditional rainbow, the agency adds. As a result, they are sometimes called “white rainbows” or “ghost rainbows.”

California’s Bay Area is famous for its fog, which rolls in from the Pacific Ocean onto the coast and through the Golden Gate between San Francisco and Marin County to the north.

The fog is such a common occurrence in the area that some locals have named the weather phenomenon “Karl”.