Northern Latitudes Have Least Amount of Daylight Near December Solstice

Summary: Earth’s northern latitudes have the least amount of daylight near the December solstice, which opens the Northern Hemisphere’s astronomical winter.

On Friday, Dec. 28, 2012, seven days after the Dec. 21, 2012, winter solstice, Anchorage, Alaska, experienced 5 hours 33 minutes of daylight and 18 hours 27 minutes of darkness; Anchorage, at sunset, Friday, Dec. 28, 2012, 15:48 (3:48 p.m.) Alaska Standard Time: Ed Schipul (eschipul), CC BY 2.0 Generic, via Flickr

Earth’s northern latitudes have the least amount of daylight near the December solstice, the end-of-year phenomenon that signals astronomical winter in the Northern Hemisphere.

The 2019 December solstice takes place Sunday, Dec. 22, at 04:19 Coordinated Universal Time. The world’s time zones convert Coordinated Universal Time, the world’s primary time standard, into local time. The 2019 December solstice takes place Saturday, Dec. 21, or Sunday, Dec. 22, according to local time zones.

The U.S. Naval Observatory’s (USNO) Astronomical Applications Department notes that the sun’s lowest arc traversal across the sky occurs in late December for northern latitudes. The sun’s daily path appears lower, more southerly and, from horizon to horizon, shorter in winter than in summer at northern latitudes. The sun rises after the start, and sets before the end, of daily routines.

The Astronomical Applications Department explains: “The changing times of sunrise and sunset are probably more noticeable in the winter months, because sunrise and sunset occur when we are more likely to be paying attention -- when we’re starting our day and during the evening rush hour.”

At the instant of December’s solstice, the tilt of Earth’s rotational axis favors the Southern Hemisphere. The south polar terminus of Earth’s axis tilts toward the sun while the north polar terminus tilts away from the sun.

The December solstice annually pairs with the June solstice as openers of summer and winter. The June solstice initiates astronomical summer in the Northern Hemisphere and astronomical winter in the Southern Hemisphere. Six months later, December’s solstice balances June’s astronomical seasons by occurring as a winter solstice in the Northern Hemisphere and as a summer solstice in the Southern Hemisphere.

At the instant of June’s solstice, the tilt of Earth’s rotational axis favors the Northern Hemisphere. The north polar terminus of Earth’s axis tilts toward the sun while the south polar terminus tilts away from the sun.

The U.S. Naval Observatory’s Astronomical Applications Department website tabulates the duration of daylight or darkness over one year for any year between 1700 and 2100. Durations are available for the United States as well as for any location worldwide.

Washington, D.C., experiences the Northern Hemisphere’s 2019 winter solstice Saturday, Dec. 21, 2019, at 11:19 p.m. Eastern Standard Time (EST). The USNO Astronomical Application’s daylight duration calculator identifies Saturday, Dec. 21, and Sunday, Dec. 22, as the two days with the least amount of daylight in 2019 for Washington, D.C. Each of the two dates has only 9 hours 26 minutes of daylight. The duration of darkness totals 14 hours 34 minutes for each of the two dates.

Alaska’s largest city, Anchorages, places the instant of the 2019 December solstice at 7:19 p.m., Saturday, Dec. 21, according to Alaska Standard Time (AKST). The December 2019 and the next day, Sunday, Dec. 22, claim Anchorage's lowest amount of daylight hours, with a duration of 5 hours 27 minutes.

Duration of daylight dwindles to zero in Utqiagvik (previously known as Barrow), Alaska’s northernmost city. Utqiagvik experiences 24 hours of darkness from Tuesday, Nov. 19, 2019, through Wednesday, Jan. 22, 2020.

Location north of the Arctic Circle qualifies Utqiagvik for the phenomenon of polar night. Polar night and its opposite, midnight sun, only occur within the polar circles. Alaska is the only part of the United States that undergoes polar nights. The phenomenon also happens in parts of Canada, Greenland, Scandinavia (Finland, Norway, Sweden) and Russia.

The takeaway for northern latitudes having the least amount of daylight near the December solstice is that the sun’s apparently lower, shorter, more southerly track across Northern Hemisphere skies around December’s solstice symptomizes the north polar tilt away from the sun during Earth’s orbital period.

Northern Hemisphere viewpoint of the sun’s apparent tracks in summer and in winter: Public Domain, via U.S. Naval Observatory Astronomical Applications Department

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

On Friday, Dec. 28, 2012, seven days after the Dec. 21, 2012, winter solstice, Anchorage, Alaska, experienced 5 hours 33 minutes of daylight and 18 hours 27 minutes of darkness; Anchorage, at sunset, Friday, Dec. 28, 2012, 15:48 (3:48 p.m.), Alaska Standard Time: Ed Schipul (eschipul), CC BY 2.0 Generic, via Flickr @ https://www.flickr.com/photos/eschipul/8336815657/

Northern Hemisphere viewpoint of the sun’s apparent tracks in summer and in winter: Public Domain, via U.S. Naval Observatory Astronomical Applications Department @ http://aa.usno.navy.mil/faq/docs/rs_solstices.php

For further information:

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Marriner, Derdriu. “American Samoa Has Autumn Equinox While United States Has Spring Equinox.” Earth and Space News. Wednesday, March 1, 2017.
Available @ https://earth-and-space-news.blogspot.com/2017/03/american-samoa-has-autumn-equinox-while.html

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Available @ http://aa.usno.navy.mil/cgi-bin/aa_durtablew.pl?form=1&year=2012&task=-1&state=AK&place=anchorage

U.S.N.O. Astronomical Applications Department. “Anchorage, Alaska: Duration of Darkness for 2019.” U.S. Naval Observatory Astronomical Applications Department > Data Services > Rise/Set/Transit/Twilight Data.
Available @ http://aa.usno.navy.mil/cgi-bin/aa_durtablew.pl?form=1&year=2019&task=1&state=AK&place=anchorage

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Available @ http://aa.usno.navy.mil/cgi-bin/aa_durtablew.pl?form=1&year=2019&task=-1&state=AK&place=anchorage

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Available @ http://aa.usno.navy.mil/cgi-bin/aa_rstablew.pl?ID=AA&year=2012&task=0&state=AK&place=anchorage

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Available @ http://aa.usno.navy.mil/cgi-bin/aa_durtablew.pl?form=1&year=2020&task=1&state=AK&place=barrow

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