Earth

A fogbow is cousin to a rainbow

A fuzzy white arc in a blue sky above a bucolic scene with a red barn and a shed.
View at EarthSky Community Photos. | Sterling Johnson in Madison, Indiana, captured this fogbow on October 21, 2023, and wrote: “I was walking back from the barn and as I looked across the field I saw this white rainbow or fogbow. Its beauty stopped me in my tracks.” Thank you, Sterling!

A fogbow, or white rainbow

Fogbows also go by the names white rainbow, cloudbow or ghost rainbow. They’re made much as rainbows are, from the same configuration of sunlight and moisture. Rainbows happen when the raindrops fill the air. You always see a rainbow in the direction opposite the sun. Fogbows are much the same, always opposite the sun. But the small droplets inside a fog or cloud create fogbows as compared to larger raindrops that create rainbows.

Look for fogbows in a thin fog when the sun is bright. You might see one when the sun breaks through a fog. Or watch for fogbows over the ocean.

Because the water droplets in fog are so small, fogbows have only weak colors or are colorless.

The 2024 lunar calendars are here! Best Christmas gifts in the universe! Check ’em out here.

Beach and water with very low, fuzzy white cloudy arc at horizon and blue sky above.
View at EarthSky Community Photos. | Angie Reagan in South Lake Tahoe, California, captured this image on April 9, 2023. Angie wrote: “I was waiting for this to turn into a rainbow, but I later learned from my friend, Amheric, that this is actually a fogbow and perhaps even more special. On this day, it was just the source of light I needed.” Thank you, Angie!

More on the search for fogbows

Les Cowley of the great website Atmospheric Optics says:

Look away from the sun and at an angle of 35-40 degrees from your shadow, which marks the direction of the antisolar point [point directly opposite the sun]. Some fogbows have very low contrast, so look for small brightenings in the misty background. Once caught, they are unmistakable.

The sun must be less than 30-40 degrees high, unless you are on a hill or high up on a ship where you can see the mist and fogbow from above.

Fogbows are huge, almost as large as a rainbow and much, much broader.

Look here for Les Cowley’s explanation of how fogbows form.

Fogbow photos from the EarthSky community

A white arch in a blue sky on a quiet street.
View at EarthSky Community Photos. | Barb Lambert in Sacramento, California, captured this image on November 7, 2023. Barb wrote: “Saw while on morning walk, never thought I’d see a fogbow. Could see both sides before connecting bow.” Thank you, Barb!
Fuzzy white arc over a shoreline, as seen from a hill, with pink flowers in the foreground and a distant lighthouse.
View at EarthSky Community Photos. | Cecille Kennedy in Newport, Oregon, caught this image of a fogbow on July 16, 2021. Cecille wrote: “What appears like a white rainbow in this photo is a natural phenomenon caused by fog. Thus it’s referred to as a fogbow. It appears white because the water droplets are much tinier than your average raindrop … Yaquina Head Light is in the upper right. At 93 feet [28 meters], it’s the tallest lighthouse in Oregon. The flowers are fireweed, so named because of their propensity to grow following fires. They are prevalent along the Oregon coast.” Thank you, Cecille!
Beach with low foamy waves rolling in under a fuzzy white arc, a fogbow.
View at EarthSky Community Photos. | Gene Peck in Hollywood Beach, California, captured this fogbow on October 31, 2020. Gene said “I was taking a morning walk in a clear sunny sky with an offshore fog bank. Within 20 minutes the fog moved in, enveloping the beach. I took this facing north-northwest, The fogbow lasted only a minute or 2, before the fog began dissipating.” Thank you, Gene!
High, white fuzzy arc with very, very pale pink along the top edge, above an icy river with trees on each side.
View at EarthSky Community Photos. | Sheryl R. Garrison caught this bow in Alberta, Canada, on October 26, 2020. Cloudbow or fogbow? Les Cowley of Atmospheric Optics told us: “Technically it is a cloudbow or fogbow. They are exactly the same phenomenon. But cloudbows appear in skies when there is no obvious ground level fog [as in this photo]. These bows with pastel colors and a white center need small water droplets compared to the larger raindrops of rainbows. The drops are suspended in humid air. You can sometimes see these bows when the air is freezing if the water drops remain supercooled and do not freeze.”

More fogbow photos

High, fuzzy white arc in misty air over a semi-tropical wooded landscape.
View at EarthSky Community Photos. | Peter Lowenstein caught this fogbow in Mutare, Zimbabwe, on April 29, 2020. Peter wrote: “Half an hour after the sun rose behind my house, a beautiful fogbow developed in the middle of a misty morning view from my front veranda. All the conditions were right, bright sunshine from the rear with the sun less than 20 degrees above the horizon and clearing clouds of mist at the antisolar point. The scene was framed by a beautiful flowering poinsettia to the left, a lush banana grove to the right, and clear blue sky beginning to appear on top!” Thank you, Peter!
Nearly semicircular fuzzy white arc with very faint colors over a red-soil desert landscape.
View at EarthSky Community Photos. | Alan Nicolle in New South Wales, Australia, captured this image on July 16, 2019. Alan wrote: “I was out geocaching in the outskirts of Broken Hill, when I turned back to see this fogbow developing. I took quite a few photos with the iPhone, and rode back to the car on my bike. But, by the time I got back to the car to use my SLR, it had faded.” Thank you, Alan!
Partial white, fuzzy arc over bucolic scene with white fence and barn in distance.
Greg Diesel Walck Photography wrote in October 2015: “Saw my first fogbow/white rainbow. Photo taken with cell phone. Moyock, North Carolina.” Thank you, Greg!

Bottom line: A fogbow looks like a white or colorless rainbow. They appear opposite the sun. Watch for them in a thin fog, when the sun is bright. You might see one when the sun breaks through a fog. Or watch for fogbows over the ocean.

Posted 
November 2, 2023
 in 
Earth

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