Alpenglow is the rosy or cherry-red glow on snow-covered mountains at sunrise or sunset. Strictly it means the indirect glow seen when the sun itself is already below the horizon; dictionaries also allow the looser sense of any reddish sunrise or sunset light on a summit.
Not attributable — a loan translation rather than a coinage.
// Where it sits
The strict definition requires the sun to be gone. Most photos labelled alpenglow aren't.
What it really means
Most photographs captioned alpenglow aren't. They show low-angle sunlight on a summit — which is beautiful and entirely ordinary, since the sun is still up and doing what suns do.
True alpenglow happens after the sun has set. No direct sunlight reaches the peak at all. What lights it is backscatter: red wavelengths that have survived a long, low path through the atmosphere, bouncing off ice crystals, water droplets and airborne particles and arriving at the mountain sideways, from a source that is no longer above the horizon.
That's why it looks impossible in person. Everything below is in shadow, the valley has gone blue, the sun is demonstrably gone — and the mountain is still burning pink, lit by nothing you can point at.
The colour isn't in the snow. Snow is doing the least interesting job available: it's a bright neutral screen, showing you what the atmosphere is sending. The same light hitting dark rock would barely register.
And the word is more literal than it looks. German Alpenglühen — the Alps glowing. The first element is a proper noun, so the term originally described one mountain range and got generalised afterwards. Every alpenglow outside Europe is, etymologically, borrowing the Alps' name for something the Alps were simply first to be described doing.
Where it comes from
The first element is a proper noun. The word literally means 'the Alps glowing', though in use — in German as in English — it applies to any mountain.
Myths & misconceptions
Alpenglow is just sunset light hitting the peaks.
In the strict optical sense no — though dictionaries also record the looser everyday sense, which is the one most photography writing uses. True alpenglow occurs when the sun is ALREADY BELOW the horizon, so no direct sunlight reaches the peak at all. The illumination is backscattered from particles low in the atmosphere. Direct low-angle sun on a summit is a different and more ordinary thing.
It's caused by the snow being pink.
The colour is atmospheric, not from the surface. Long red wavelengths survive the long low-angle path and are reflected from ice crystals, water droplets and particulates; the snow is simply a bright neutral screen.
Compare & contrast
Alpenglow vs the Belt of Venus
Both are backscattered twilight red, and they're two halves of one scene. The Belt of Venus is the pink anti-twilight arch in the sky opposite the sun, sitting above the blue band of Earth's own shadow. Alpenglow is that same light landing on a mountain face.
| // | Alpenglow | Belt of Venus |
|---|---|---|
| Where | On a mountain | In the sky |
| Direction | Opposite the sun | Opposite the sun |
| Light source | Backscattered | Backscattered |
| Needs mountains | Yes | No |
How it connects
- Green Flashboth depend on light taking a long, low path through the atmosphere.
- Gloamingboth name a specific quality of light after the sun has gone.
Tell it apart
Questions people ask
- When does alpenglow happen?
- Just before sunrise or just after sunset, when the sun is below the horizon and cannot illuminate the peak directly. If the sun is still up and shining on the summit, that is direct low-angle light. Dictionaries count that as alpenglow too; the strict optical sense does not.
- Is alpenglow the same as the Belt of Venus?
- Related but distinct. Both come from backscattered red light; the Belt of Venus is the pink arch in the sky opposite the sun, above the blue band of Earth's own shadow. Alpenglow is that light striking mountains.
- Do you need snow?
- It's most apparent on snow-covered mountains, since snow makes an ideal bright neutral screen. The atmospheric effect exists regardless — snow just shows it best.