The Collaborative International Dictionary
Alpenglow \Al"pen*glow`\, n. A reddish glow seen near sunset or sunrise on the summits of mountains; specif., a reillumination sometimes observed after the summits have passed into shadow, supposed to be due to a curving downward (refraction) of the light rays from the west resulting from the cooling of the air.
Wiktionary
n. A rosy or reddish glow seen during sunset or sunrise on the summits of mountains, especially snow-covered mountains on the opposite side of the sun.
Wikipedia
Alpenglow (from German: Alpenglühen) is an optical phenomenon in which a horizontal red glowing band is observed on the horizon opposite to the sun. This effect occurs when the Sun is just below the horizon. Alpenglow is easiest to observe when mountains are illuminated but can also be observed when the sky is illuminated through backscattering.
Since the Sun is below the horizon, there is no direct path for the light to reach the mountain. Unlike sunset or sunrise, the light that causes alpenglow is reflected off airborne snow, water, or ice particles low in the atmosphere. These conditions differentiate between a normal sunrise or sunset and alpenglow.
Although the term may be loosely applied to any sunrise or sunset light seen on the mountains, true alpenglow is not direct sunlight and is only observed after sunset or before sunrise.
In the absence of mountains, the aerosols in the eastern portion of the sky can be illuminated in the same way at sunset by the remaining red scattered light straddling the border of the Earth's own shadow (the terminator). This back-scattered light produces a red band opposite the Sun.
Usage examples of "alpenglow".
But as he stared at alpenglow from the dying sunset, he saw all the difference that mattered.
Himalayas, knowing a mate must be somewhere up there among the alpenglow and mist.
Next he was on gravel, gaining speed again, spinning up a swirl of dust behind him as he drove on toward the house and barn, their structures now in dusk, the alpenglow abruptly gone, the sun behind the mountains.
When Marge arrived tonight, she would watch over Dunlap while the one-armed man and the son in need of a father would ride out to check the steers, and in the meantime, Slaughter leaned back, smiling, as the setting sun cast an alpenglow on Lucas who rode straight and strong, and a colt veered from its mother, and they gamboled in the sun.
If you camp on this prominence, in the alpenglow the distant range looks like the side of a different world, rolling slowly up into the sky.
Night was coming on and alpenglow had turned Everest into a vast crimson spike.
Chinese and Tibet and the mountain, finally dropping into an exhausted silence as alpenglow lit Everest orange.
Buccari, hands and face blackened with soot, collapsed on the lodge porch and watched the sun flush alpenglow from the snowy peaks.
He headed for the fountain to wait for his grandson, treading like a snow leopard across the Himalayas, knowing a mate must be somewhere up there among the alpenglow and mist.
Just after sundown, as the Andes valleys were bathed in alpenglow, Daeman, Tom, and Siris freefaxed in, but they stayed only a few moments.
The lower ranges were forested, as was the valley between, and there was a redmauve alpenglow on the great peak that rose from the head of the valley.
I folded my arms and looked out at the alpenglow illuminating the cloudtops many kilometers below and the brilliant evening light on the northern peak.
I confess that I am disappointed: we had planned to arrive at Potala in the twilight, while there was still alpenglow lighting the north-south ridges and the higher peaks to the north and west of the palace.
The lower ranges were forested, as was the valley between, and there was a red-mauve alpenglow on the great peak that rose from the head of the valley.
The sun had just set, and the alpenglow was so strong that it looked like she was standing in her own blood, as if she were a creature as small as a cell standing on the corroded wall of her heart, while around her swept the winds of her own dusty plasma.