Why is the sky pink at sunset?

Where does pink come from?

Pink is what you get when red light is mixed with white or blue. At sunset the sun's light is reddened by its long trip through the air. Clouds and fine particles scatter that light across the sky, and by the time it reaches your eye it is a softer, paler red than the direct beam. That is pink.

This is the same physics behind the red of the sun itself, explained in why sunsets are red. Wikipedia notes that the reddened sunlight can be scattered by cloud droplets and other large particles to light up the horizon red and orange (Wikipedia: Sunset).

What is the Belt of Venus?

It is a pinkish glow that surrounds the observer, extending roughly 10 to 20 degrees above the horizon, visible shortly before dawn or after dusk, opposite the sun. Wikipedia describes it as the antitwilight arch, caused by the backscatter of reddened sunlight by fine particles high in the atmosphere (Wikipedia: Belt of Venus).

Under it sits a darker blue-gray strip, which is the shadow of the Earth itself projected onto the sky. As twilight deepens, the shadow rises and the pink band lifts away from the horizon.

Why is pink stronger in some seasons?

Wikipedia says the Belt of Venus appears vivider pink during the winter months, and faded and dim above a yellowish-orange band near the horizon in summer. The explanation is that colder air holds less absolute humidity, so it is clearer and more stable. If you live somewhere with cold, dry winters, the pinkest evenings may come then.

What is alpenglow?

Alpenglow is a reddish glow near the horizon opposite the sun, seen when the solar disc is just below the horizon. Strictly it refers to indirect sunlight reflected off airborne particles, ice crystals or precipitation onto mountains, though the word is also used loosely for any rosy light on peaks at dawn or dusk (Wikipedia: Alpenglow). If no mountains are present, the same effect in the east is the Belt of Venus.

Why are some sunsets pinker than others?

Pink needs a canvas. Thin high clouds, a bit of haze and fine particles give the scattering a surface to land on. A cloudless sky tends toward orange near the horizon and plain blue above. A thick gray ceiling gives almost no pink. The best pink often shows up when the western sky has high cloud and the air is dry and clean, a pattern that matches the factors in the Glow Score.

When should I look for pink?

In two moments. First, just before and after the sun disappears, when clouds overhead are lit from below. Second, 10 to 20 minutes after sunset, when you turn around and look east. The second is the one people miss, because everyone faces the sunset. A viewpoint with an open east horizon lets you enjoy both, and our piece on which direction the sun sets can help you choose one.

Does pink show up in photos?

Often more strongly than in real life, because phone cameras raise saturation in dim light. Lowering exposure slightly keeps the pink from turning magenta, and a gentle tweak in the Photos app handles the rest. The guide to editing sunset photos on iPhone has the order of sliders I would use.

Is a pink sky a sign of good weather?

The saying "red sky at night" is often extended to pink, and some versions of the rhyme use pink in place of red. As described in our article on red sky at night, sailors delight, the idea works best in mid-latitudes, where weather moves from west to east, and it is not a precise forecast. Treat a pink evening as a nice sky, with a mild hint about the air, not as a guarantee about tomorrow.

Why is pink so common in photos?

Phone cameras raise saturation and shift white balance in dim light, so a faint pink in real life can become a strong magenta on screen. Photos taken at twilight also compress color, so purple and pink merge. If your photo looks more pink than the evening felt, lower the exposure a little and reduce Vibrance in the Photos app. The aim is to keep the pink that was there.

Can I find the pink part in my own sky log?

Yes. Each chip in Afterhue keeps five hex codes ordered from the top of the sky to the horizon. Pink evenings usually show a rose or lilac swatch in the middle and a warm one at the bottom. Browsing your chips by color is a quick way to find the evenings you liked best, and the month grid shows them as swatches on the days you caught them.

How can I save a pink evening?

When you photograph the sky in Afterhue, it reads five colors and orders them top of the sky first, so the pink band and the lilac above it appear as separate swatches on the Hue Chip. Afterhue names palettes such as Apricot Static or Lilac Afterglow, and you can rename a chip with up to 28 characters. A pink evening becomes something you can find again.