What Is Alpenglow?
Alpenglow is the reddish-pink glow that lights up mountain peaks on the side of the sky opposite the sun, just before sunrise or just after sunset, when the sun itself is already below the horizon. More loosely, people use the word for any rosy light on peaks at sunrise or sunset, including the last minutes of direct sun.
By Andrew YatesForecasting sunrises and sunsets since 2016
Know when the glow will be good
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What causes alpenglow?
The word comes from the German Alpenglühen, "Alps glow", and the color comes from the same physics that makes sunsets red. When the sun is low, its light crosses a very long, shallow path through the atmosphere. Along the way, air molecules scatter the shorter blue wavelengths out of the beam (Rayleigh scattering), so what is left is orange, red and pink.
Mountains add height. A summit a few thousand metres up still sees the sun after the valley floor has fallen into shadow, so you can watch the line of sunlight climb the face and slip off the top. Then, once the sun has set even for the summit, something subtler takes over: the peaks are still lit, faintly, by sunlight that has been scattered and bent through the atmosphere on the sunset side of the sky. That indirect, reddened light is alpenglow in the strict sense, and it is why the snow can turn a soft pink after the direct sun has already gone.
Some writers keep the two apart: warm direct sunlight on the peaks at sunrise and sunset (sometimes called alpine glow), and true alpenglow once the sun is below the horizon. Most people, and most photographers, use "alpenglow" for both. If you stay put after the first glow fades, you may also see a second, fainter glow a few minutes later, as light from higher in the twilight sky briefly brightens the peaks again.
Where and when to see it
- Face away from the sun
- At sunset, look east toward mountains whose west-facing slopes catch the last light. At sunrise, look west at east-facing slopes. Mount Rainier from Seattle at sunset and the Front Range from Denver at sunrise are classic examples.
- Watch the minutes either side of the sun crossing the horizon
- The direct-sun glow peaks just before sunset (or just after sunrise); true alpenglow follows in the first minutes after sunset (or comes before sunrise).
- Clear air toward the sun
- The light has to reach the peaks from the sunset side, so a bank of low cloud on that horizon can switch alpenglow off entirely. Clean, dry air gives the strongest color; haze and high humidity mute it.
- Bright surfaces
- Snow, ice and pale rock reflect the color best, which is why snow-capped ranges and light granite or limestone walls glow so well.
Exact timing depends on your location and the date. The sun direction calculator shows where the sun sets and rises, so you can work out which faces of a mountain will catch the light.
How long does alpenglow last?
Not long. The direct-sun glow on the summits lasts only as long as the shadow line takes to climb the mountain, and true alpenglow usually fades within a few minutes of sunset. All of it happens well inside civil twilight, which ends when the sun is 6° below the horizon. Closer to the poles, where the sun crosses the horizon at a shallow angle, every stage of twilight stretches out and the glow can linger noticeably longer.
Alpenglow vs golden hour, blue hour and the Belt of Venus
These are easy to mix up because they overlap in time, but they are different things.
- Golden hour
- A time window. In the evening it runs from when the sun is about 6° above the horizon until sunset: roughly 20–30 minutes near the equator, 30–60 minutes at mid-latitudes, and longer at high latitudes. Everything gets warm, direct light. Plan it with the golden hour calculator.
- Blue hour
- Runs from sunset to the end of civil twilight (sun 6° below the horizon), about 20–40 minutes at mid-latitudes, when the sky turns deep blue. The blue hour calculator gives exact times.
- Alpenglow
- Not a time window but a glow on mountains. It sits at the seam between the two: the end of golden hour and the first minutes of blue hour in the evening, and the reverse at dawn.
- The Belt of Venus
- The pink band above the horizon opposite the sun just after sunset or before sunrise. Beneath it is a dark blue-grey band, the Earth's shadow, cast onto the atmosphere. The Belt of Venus is the same reddened, backscattered light as alpenglow, seen on the sky instead of on rock and snow, which is why the two often appear together.
How to photograph alpenglow
- 1Be in place early
- Arrive 30–45 minutes before sunset so you are set up for the end of golden hour, and plan to stay 20 minutes after it.
- 2Don't pack up at sunset
- True alpenglow and the second glow come after the sun has gone, when most people are already walking back.
- 3Use a tripod
- Light drops quickly, and longer exposures at a low ISO keep the snow clean and the shadows free of noise.
- 4Protect the highlights
- Lit snow is the brightest thing in the frame. Expose for it, or bracket and blend, so the pink doesn't clip to white.
- 5Fix your white balance
- Auto white balance tends to neutralize the pink. A daylight preset, or shooting raw, keeps the color as you saw it.
- 6Reach for a longer lens
- A short telephoto isolates the glowing summit against the darkening sky; a still lake gives you a reflection for free.
Why our app is called Alpenglow
Alpenglow is named after this light: the moment, just after the sun has gone, when the sky still has one more thing to show you. The app itself isn't limited to mountains. It forecasts how good sunrises and sunsets will be anywhere in the world, scoring each one from Poor to Great based on cloud cover at different altitudes, moisture and air quality, so you know when it's worth heading out.
You can read how the scores are calculated on the forecast model page, check whether tonight's sunset will be good, or download Alpenglow for iPhone, Android, Mac and Apple Watch.
Frequently asked questions
What does alpenglow mean?
The word comes from the German Alpenglühen, literally "Alps glow". Strictly, it describes the rosy light on mountains seen just after sunset or before sunrise, when the peaks are lit by sunlight scattered through the atmosphere rather than by the sun directly. In everyday use it also covers the pink and orange light on peaks during the last and first minutes of direct sun.
What is the difference between alpenglow and golden hour?
Golden hour is a window of time when the sun is low, up to about 6° above the horizon, and lights the whole landscape with warm, direct light. Alpenglow is a specific glow on mountains that peaks right around sunset or sunrise and continues for a few minutes while the sun is below the horizon, so it sits at the very end of evening golden hour and the start of blue hour.
When can you see alpenglow?
Look for it in the few minutes either side of sunset and sunrise. At sunset, face east toward mountains whose west-facing slopes catch the last light; at sunrise, face west toward east-facing slopes. Clear air toward the sun and snow or pale rock on the peaks give the strongest color.
How long does alpenglow last?
Usually only a few minutes. The glow fades as the sun sinks further below the horizon, and it falls well inside civil twilight, which ends when the sun is 6° below the horizon. At high latitudes, where the sun sets at a shallow angle, it can linger noticeably longer.
Can you see alpenglow without mountains?
Not in the strict sense, because the word describes light on peaks. But the same reddened light colors tall clouds, high-rise buildings and the Belt of Venus, the pink band that sits above the dark blue shadow of the Earth on the horizon opposite the sun.
Is the Alpenglow app only for mountain sunsets?
No. The app is named after the phenomenon, but it forecasts how colorful sunrises and sunsets will be anywhere in the world, from cities and coastlines to deserts and mountains.
