Where to see alpenglow

To immerse yourself in alpenglow, go to a location with a clear view of the Indian Peaks or go for a dawn ski tour. Favorite places include:

White Rocks Trail starting at North Teller Farms Trailhead on Valmont Road.

Pella Crossing on 75th Street, south of Hygiene.

Golden Ponds and Fairground Lake off Hover Road in Longmont.

Other January atmospheric astonishments

Iridescent clouds spread across the sky in broad sheets when ice crystals in cirrus clouds near the sun refract sunlight into opalescent colors. The brightness is enhanced when the crystals are more numerous and uniform in size.

"Sundogs," which look like patches from a rainbow, and "haloes" -- also caused by light refraction -- develop at either 22 or 44 degrees from the sun. They can be seen any time of year but are most conspicuous when the sun is low.

Moon haloes, like ghostly circular rainbows, happen when ice crystals refract moonlight. (Since moonlight is really sunlight reflected by the moon, would you call this a refraction of a reflection?) Sometimes a double moon halo extends out to about 22 degrees from the moon with repeated bands of gold, red, violet, blue and green.

The Quadrantid meteor shower, brief but intense, peaks on Jan.


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3. Under dark, moonless skies, more than 100 meteors per hour may be seen, but the moon, three days past full, will dim the 2010 show.

Photo by Glenn Cushman

Photo by Stephen Jones

If you get up before sunrise and if atmospheric conditions are right, you may catch that magic moment when mountains blush.

Depending on where you are in the world, this phenomenon is called alpenglow, or alpengluhen, or enrosadira.

According to "The Harper Encyclopedia of Science," alpenglow results from a "scattering of white light by particles suspended high in the atmosphere during the few minutes the sun is just below the horizon." The radiance happens when low rays of the sun illuminate clouds that then reflect down onto high places.

Other dictionaries, however, define alpenglow simply as the rosy light of the setting or rising sun on mountains. Although true alpenglow is reflected -- not direct -- light, most of us call any low-angle, pink light that suffuses the mountaintops "alpenglow."

Alpenglow intensifies when it shines on the red rocks of the canyon country as it did from this plateau near Goblin Valley, Utah, at sunset.
Alpenglow intensifies when it shines on the red rocks of the canyon country as it did from this plateau near Goblin Valley, Utah, at sunset. (Glenn Cushman)

Maybe the explanation lies in the German legend of Laurin, king of the dwarfs, who created a lustrous rose garden on the rock face of a mountain. Captured and tortured by a jealous king who coveted the roses, Laurin cursed them and cast a spell so no one would ever again see them night or day. But he forgot dawn and evening, and that is when we still delight in his enchanted roses.

In Boulder, we see alpenglow when the sun lies just below the eastern horizon and illuminates the mountains to the west; on the Western Slope, alpenglow happens after sunset when the sun's rays light up mountains to the east.

The same effect can inflame any high object, such as the Flatirons or Utah's red rock canyons. Alpenglow can even transform white gulls flying overhead to petal pink or magpies to magenta and black.

January is the perfect time to observe alpenglow because the mountains are usually luminous with snow, and the latest sunrises of the year make it easier for us to rise before the sun. Although daylight hours lengthen following winter solstice, the process is not symmetrical. This year, sunrise gets stuck at 7:23 a.m. from Dec. 30 until Jan. 11. By the month's end, the sun rises at 7:10 a.m.

Early risers should also look for the Belt of Venus, a Victorian-era name for a lavender-pink arch that sometimes extends from 10 to 20 degrees above the horizon shortly before sunrise or after sunset. This eerie, ethereal light appears on the opposite side of the sky from the sun and is separated from the horizon by a dark-bluish layer that is the shadow of the Earth.

Ruth Carol Cushman and Stephen Jones are authors of "Wild Boulder County" and "Peterson Field Guide to North American Prairie."