A fog bow is a similar phenomenon to a rainbow, however, as its name suggests, it appears as a bow in fog rather than rain. Because of the very small size of water droplets that cause fog—smaller than 0.05 millimeters (0.0020 in)—the fog bow has only very weak colors, with a red outer edge and bluish inner edge.
In many cases when the droplets are very small, fog bows appear white, and are therefore sometimes called white rainbows. This lack of color is a feature of a fog bow which distinguishes it from a glory, which has multiple pale colored rings caused by diffraction. When the droplets forming it are almost all of the same size the fog bow can have multiple inner rings, or supernumeraries, that are more strongly colored than the main bow. According to NASA:
The fogbow's lack of colors is caused by the smaller water drops ... so small that the wavelength of light becomes important. Diffraction smears out colors that would be created by larger rainbow water drops ...
A fog bow seen in clouds, typically from an aircraft looking downwards, is called a cloud bow. Mariners sometimes call fog bows sea-dogs.
Read more about Fog Bow: Direction
Famous quotes containing the words fog and/or bow:
“as if in a fog of feather-light
goosedown-silvery seed-thoughts
a rusty mind in its autumn
reviewed, renewed
its winged power.”
—Denise Levertov (b. 1923)
“Verily, the Indian has but a feeble hold on his bow now; but the curiosity of the white man is insatiable, and from the first he has been eager to witness this forest accomplishment. That elastic piece of wood with its feathered dart, so sure to be unstrung by contact with civilization, will serve for the type, the coat-of-arms of the savage. Alas for the Hunter Race! the white man has driven off their game, and substituted a cent in its place.”
—Henry David Thoreau (1817–1862)