The Spectral Colors of Brocken Bows and Glories

Imagine hiking on a sunny mountain and witnessing an unforgettable phenomenon worthy of a Hollywood special effects team: as a bank of chilly fog rises from a couloir, your shadow grows to gigantic proportion (hundreds of feet high), surrounded by a prismatic halo.

In olden times, the spectre was considered to be of supernatural origin and fearfully ominous in nature. Today, the phenomenon is known as a "Brocken Bow," named after a mountain in Germany. Like a small, circular rainbow, a foggy Brocken Bow tends to last from several seconds to fifteen minutes. Bands of color surround the gigantic shadow at a distance of several feet. The outermost band is red, and the others follow the order of the typical rainbow. In some cases, a Brocken Bow is surrounded by a second bow, whose color order is reversed. A similar phenomenon, known as a Glory, is distinguished by the fact that the bands of color touch the head of the shadow. Glories typically sport seven bands of color and can last for hours at a time. Sometimes Glories are surrounded by glowing white fog bows.

by bob the lomond

In ideal conditions, the sun shines behind the observer and a cloud of fog rises from a lower elevation in front. The ideal temperature for Brocken Bows and Glories varies between 19 and 56 degrees Fahrenheit. Though the bands of colors are no illusion, the size of the shadow is actually a trick of the eye. Apparently, the shadow appears gigantic due to a distortion of depth caused by moving fog particles at varying distances.

For a detailed description of Brocken Bows and Glories from a scientific point of view, see Henry Sharpe's piece for Scottish mountaineers. Also don't miss The Nonist's study on the phenomenon, illustrated with vintage woodcuts and color photographs.

by bob the lomond

[Read the entire article in my guest blog at ColourLovers.com.]

All the Colors of the Wind

The air. A thing too intangible for color you think? ... The truth is all air is colored.
—John C. Van Dyke, The Desert

Anyone who thinks that air is invisible is impaired by a sort of color blindness. Indeed, the air is so alive with color that it could be likened to a rainbow that encircles the entire earth with pink, red, violet, gray, blue, and yellow. Ask a naturalist or a painter, and you'll hear descriptions of an airy spectrum that escapes the unobservant viewer. Carried by swirling dust particles and refracted by the prisms of water vapor, the colors of the air are best observed in a mass. Mountaintop vantages, canyons, desert expanses, or deep valley views are recommended. The warmer the temperature and the stronger the wind, the more color will be detectable. Rising heat carries finer dust particles deepening the air's hues, while high winds carry larger particles, brightening the coloration.¹

Here's how naturalist Richard Jefferies poetically recorded seeing the colors of the wind at sunrise one morning:

by James Jordan.

Color comes up in the wind; the thin mist disappears, drunk up in the grass and trees, and the air is full of blue behind the vapor. Blue sky at the far horizon — rich deep blue overhead — a dark-brown blue deep yonder in the gorge among the trees. I feel a sense of blue color as I face the strong breeze; the vibration and blow of its force answer to that hue, the sound of the swinging branches and the rush — rush in the grass is azure in its note ; it is wind-blue, not the night-blue, or heaven-blue, a color of air. To see the color of the air, it needs great space like this — a vastness of concavity and hollow — an equal cauldron of valley and plain under, to the dome of the sky over, for no vessel of earth and sky is too large for the air-color to fill. Thirty, forty, and more miles of eye-sweep, and beyond that the limitless expanse over the sea — the thought of the eye knows no butt, shooting on with stellar penetration into the unknown. In a small space there seems a vacuum, and nothing between you and the hedge opposite, or even across the valley; in a great space the void is filled, and the wind touches the sight like a thing tangible. The air becomes itself a cloud, and is colored — recognized as a thing suspended; something real exists between you and the horizon. Now, full of sun and now of shade, the air-cloud rests in the expanse.²

The COLOURlovers library is full of airy inspiration. There are colors of "thin" to "heavy" atmospheres as well as airless colors of suffocation.

NOTES:
[1] John C. Van Dyke, The Desert: Further Studies in Natural Appearances, 1903.
[2] Richard Jefferies, "Winds of Heaven," The Eclectic Magazine, 1886.

[Read the entire article in my guest blog at ColourLovers.com.]