Brilliant 'Fog Bow' greets Air Force One at Sea-Tac Airport

Air Force One is shown with sunlight hitting fog and creating a subtle fog bow following a day of Seattle fundraisers by President Barack Obama. (Photo: Jordan Stead /

Seattle put on quite a show when President Obama arrived at Sea-Tac Airport Sunday evening with a brilliant sky highlight a setting-sun-kissed Mt. Rainier.

What to do for an encore? How about an unusual "fog bow" for his departure?

A milky-white arch surrounded Air Force One as it taxied toward the Sea-Tac runway Monday morning, bringing a few looks of surprise to those in the media and Secret Service.

Fog bows are generally seen as an arc of dense fog along the edge of a fog patch. The physics is somewhat similar to traditional rainbows in that the bow is caused by sunlight refracting inside water droplets.

However, unlike rainbows, where the raindrops are large enough to refract sunlight into its individual colors, the water droplets in a fog bow are much smaller, and so the refractions aren't as precise.

Thus, the way the light scatters from a fog bow, you get a lot of color overlapping, and more of a hazy white bow instead of the colorful rainbow.