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:
“Even as fog continues to lie in the valleys, so does ancient sin cling to the low places, the depressions in the world consciousness.”
—Dewitt Bodeen (1908–1988)
“I never knowed how clothes could change a body before. Why, before, he looked like the orneriest old rip that ever was; but now, when he’d take off his new white beaver and make a bow and do a smile, he looked that grand and good and pious that you’d say he had walked right out of the ark, and maybe was old Leviticus himself.”
—Mark Twain [Samuel Langhorne Clemens] (1835–1910)