See Why Light Is Pink in Fairbanks in January
Pink sky in January in Interior Alaska

In December and January, the daylight in Interior Alaska is salmon pink. Thus, when you see an OOTD photo shot at that time of the year on a clear day, it looks like someone applied a kitschy filter or like you are looking thru pink colored shades. But actually this pinkish shades are the natural beauty of winter in the Arctic. This post explains the phenomenon and features a new look of the day.

Contents
  1. The Physics behind Blue vs. Pink Skies
  2. Air Pollution Can also Cause Pink Skies
  3. Why to Wear Sunglasses When the Sky Is Pink
  4. Is It Dark All Winter In Alaska
  5. More on Alaska’s Phenomena
  6. References

Disclosure: There are affiliate links in this post.

The Physics behind Blue vs. Pink Skies

When you live in mid-latitudes, you may have seen pink skies only during sunrise and sunset. However, at high latitudes, in winter, the sun barely comes above the horizon. Like in mid latitudes during sunrise/set, the sun beams have to travel a very long way thru the atmosphere at in Polar Regions in winter. This long distance increases the likelihood that visible light beams are scattered by gases.

graphic of length of the path a sun beam travels thru the atmosphere
At solar noon, the distance that a beam travels thru the atmosphere is the shortest (blue arrows). When the Sun is low in the sky, the light travels a comparably longer distance thru the atmosphere (red arrows) eventhough the distance Earth-Sun is about the same (dotted line). Consequently, the light can be scattered at more gas molecules.

 

The visible light ranges from ultra violet over blue, green, yellow, orange to red. You can see this when light is split into its components by a prism or the raindrops of a rainbow.

The atmospheric molecules scatter UV and blue light over and over again (Rayleigh Scattering). This makes the sky look blue when the Sun is high above the horizon. Then the distance that the light travels thru the atmosphere is relatively short. It is the shortest at solar noon, when the Sun is in the zenith. However, at low sun zenith angle during sunrise/set in mid- and low latitudes, the light travels a long distance thru the atmosphere. The blue frequencies are scattered away. Only the orange and red frequencies of the sun beam reach the eyes. Thus, everything seems to be in a light reddish-orange hue. In Fairbanks during daylight in winter, the Sun is very low in the sky. Like in mid- and low latitudes during sunrise/set, the light has to travel a long way thru the atmosphere.

Schematic view explaning Rayleigh scattering
The blue color of the sky is caused by Rayleigh scattering of sunlight by the gases in the Earth’s atmosphere. CC BY-SA 3.0 via Wikimedia Commons. The above image shows the degree to which Rayleigh scattering scatters blue light more intensely than red light. The scattering curve shown is calculated for sunlight passing vertically through the atmosphere and is based on Bucholtz (1995). Other details, such as scattering from dust and absorption of some light by greenhouse gases are not shown.

 

Air Pollution Can also Cause Pink Skies

You can also see read skies in Alaska during times of severe wildfires and volcanic eruptions. These events lead to the emission of particles of various size. Aerosols can also build naturally in the air by gas-to-particle conversion. They are also emitted from anthropogenic sources. The more particles/aerosols are in the atmosphere, the deeper the orange and red become. The aerosols scatter the light as well. Consequently, during wildfires or when ash from volcanic eruption is in the air, the Sun may look red and the sky orange. More on air pollution in Alaska.

 

Thus, pastel pinks mean relatively few, saturated orange and reds comparatively more aerosols.

 

seemingly pink trees in Interior Alaska
Pink trees due to the low sun zenith angle in December and January in Interior Alaska

 

Why to Wear Sunglasses when the Sky Is Pink

Think of these beautiful sunrises and sunsets above the ocean. Like over the ocean, you also have a lot of glare as the snow also reflects the light. This glare is the reasons why there is no problem to find nice sunglasses in Alaska. Sunglasses sell like hotcakes.

In Polar Regions, you really need sunglasses yearround.

 

Is It Dark in Alaska All Winter?

At winter solstice, the Sun is still 2o above the horizon in Fairbanks at noon. There are about 3:42 hours of daylight on December 21. However, you only have to drive north, maybe a seven hour drive, depending on the road conditions, to Wiseman (67°26′0″N 150°5′40″W) on December 21 to have no sunrise. In Utqiagvik (formerly Barrow), the farthest north Alaskan community, the polar night starts on November 18. The Sun remains below the horizon for 66 (!) days. The Sun rises again on January 22 at 1:16 PM, just to set again at 2:02 PM. Read more about winter solstice in Fairbanks.

 

This means after 66 days of darkness, Utqiagvik has about 46 minutes of pink light, if the sky is cloudfree!

 

On the contrary, at Amatignak Island (in the Aleutian Chain), which is the southernmost point of Alaska (51.262222 N, 179.108611 W), daylight and night conditions are more comparable to those in Leipzig, Germany (51.3397 N, 12.3731 E), London, UK (51.5074 N, 0.1278 W) or Calgary, Canada (51.0447 N, 114.0719 W). Read more about Alaska daylight and white nights.

 

More on Alaska’s Phenomena

Focus Alaska is a series on Alaska curiosities, nature and lifestyle including travel insider tips. You can find further interesting posts about the State in the archive.

Do you love when the sky is pink or red? Do you adore sunsets and sunrises?

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References

Bucholtz, Anthony, 1995. Rayleigh-scattering Calculations for the Terrestrial Atmosphere, Applied Optics, 34, 2765-2773
Mölders, Nicole, Kramm, Gerhard, 2014. Lectures in Meteorology, Springer, New York.

Graphic of Sun-Earth: N. Mölders

Photos: G. Kramm, N. Mölders

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