Alpenglow
noun ‘al˙ pen˙ glow: a reddish glow seen near sunset or sunrise on the summits of mountains (Merriam-Webster dictionary)
(The following is from https://www.phenomena.org/atmospheric/alpenglow/) It is important to note that there are some discrepancies in books and internet sources on how alpenglow occurs and what it is. Some sources state that it is a result of direct light from the sun that is hidden behind the horizon. Other sources [state] that it is caused by indirect light that has been reflected off of atmosphere and other particles.
Direct Light: When alpenglow is caused by direct light, the sun has set behind the horizon from an observer’s point of view who is standing on the ground, far below the mountain tops. In this case, direct sunlight is still reaching the mountain tops, and if the observer were standing at the top of the mountains, they would see that the sun was still above the horizon.
The direct sunlight that is reaching the mountains has traveled through significant amounts of atmosphere, due to the sun’s position low on the horizon and the curvature of the Earth. When sunlight travels through more atmosphere, the small blue light waves in the sunlight get scattered, and only the longer red light waves get through.
When these red light waves reflect off the mountains, it gives them a bright pink glow. If an instance of alpenglow is caused by direct light, shadows will be present and well defined.
Indirect Light: When alpenglow is caused by indirect light, much of the mechanics are similar to when it is caused by direct light. The sun has similarly set behind the horizon for the observer on the ground, but it has also set for the observer on the mountain top.
Sunlight from the sun still has to travel through significant amounts of atmosphere, due to the sun’s position near the horizon and the curvature of the Earth. Therefore, the light waves reaching the mountains are still red. But light from the sun is no longer directly hitting the mountains. The only red light waves that are hitting the mountains have been reflected off of elements in the atmosphere.
If alpenglow is being caused by indirect light, its effect is much less pronounced than when it is caused by direct light. The hue of the mountains are a dull pink to almost purple. There are also few if any shadows. According to Wikipedia, this is the only true alpenglow, but that is very much open for interpretation. (end reference)
For the most part, I don’t position myself purposefully to capture alpenglow. Most of the time it is a happy confluence of being in the right place for viewing and the right time of day, with the right weather conditions. And, it’s not always the distant lofty mountain views that stun me; sometimes it’s right under my feet.