Ghostly Fogbow, a Colorless Rainbow, Spotted in Missouri

— -- A transparent rainbow arching across the sky was captured by a photographer who luckily caught a glimpse of the phenomenon while driving in Missouri on Monday.

"I was driving into patches of fog and I kept seeing what I thought was a rainbow," Tammi Elbert of Washington, Missouri, told ABC News today. "When I first saw it, I thought it was maybe an optical illusion. I was pretty intrigued and I knew I've seen it before I didn't realize how rare it was."

Elbert pulled over her car and snapped photos. She posted them onto her Facebook and Twitter pages, where a friend soon informed her that what she had witnessed was a "fogbow" -- a rainbow that has a white band appearing in fog that is fringed with red colors on the outside, and blue on the inside, according to the National Weather Service.

Elbert, who enjoys photographing weather and storm conditions, said the sun was shining from behind her in order for her to see the fogbow clearly.

"It's kind of eerie, they're really beautiful though," she said. "You just see this big, white rainbow and it's very usual."

According to NASA, the bow's fog and lack of colors are caused by the relatively smaller water drops: "[S]o small that the quantum mechanical wavelength of light becomes important and smears out colors that would be created by larger rainbow water drops acting like small prisms reflecting sunlight."