Editing Alpenglow

[[File:Alpenglow1a.jpg|thumb|top: reflected alpenglow; bottom: direct sunrise alpenglow from Table Mountain to Mount Baker, WA, USA.]]
{{Short description|Reddish glow on the horizon opposite the Sun just after it sets}}
[[File:Alpenglow Explanation.svg|thumb|upright=1.2|Solar ray 1 is the lowest from the Sun{{snd}}the Sun is set. Solar ray 2 is reflected in the (snow) clouds to the observer.]]

'''Alpenglow''' (from {{langx|de|Alpenglühen|lit=Alps glow}}; {{langx|it|[[wikt:enrosadira|enrosadira]]}}) is an [[optical phenomenon]] that appears as a horizontal  reddish [[afterglow|glow]] near the [[horizon]] opposite to the [[Sun]] when the solar disk is just below the horizon.<ref name=LynchLivingston2001>{{cite book |last1=Lynch |first1=David K. |last2=Livingston |first2=William |title=Color and Light in Nature |date=June 2001 |publisher=Cambridge University Press |isbn=9780521775045 |page=41}}</ref>

==Description==
Strictly speaking, alpenglow refers to indirect [[sunlight]] [[reflection_(physics)|reflected]] or [[diffraction|diffracted]] by the atmosphere after [[sunset]] or before [[sunrise]]. This diffuse illumination creates soft shadows in addition to the reddish color. The term is also used informally to include direct illumination by the reddish light of the rising or setting sun, with sharply defined shadows.

===Reflected sunlight===
When the Sun is below the horizon, [[sunlight]] has no direct path to reach a mountain. Unlike the direct sunlight around sunrise or sunset, the light that causes alpenglow is [[diffuse reflection|reflected]] off airborne [[precipitation]], [[ice crystals]], or [[particulates]] in the lower atmosphere. These conditions differentiate between direct sunlight around sunrise or sunset and alpenglow.<ref name="CD-20091228">{{Cite news |url=http://www.coloradodaily.com/ci_14082740 |title=Catch Boulder's 'alpenglow' -- blushing mountains -- this winter |last1=Cushman |first1=Ruth Carol |last2=Jones |first2=Stephen |date=December 28, 2009 |access-date=2018-01-10 |archive-url=https://web.archive.org/web/20180110114717/https://www.coloradodaily.com/ci_14082740 |archive-date=2018-01-10 }}</ref>

The term is generally confused to be any sunrise or sunset light reflected off the mountains or clouds, but alpenglow in the strict sense of the word is not direct sunlight and is only visible after sunset or before sunrise.<ref name=LynchLivingston2001/>

After sunset, if mountains are absent, [[aerosols]] in the eastern [[sky]] can be illuminated in a similar way by the remaining scattered reddish light above the fringe of [[Earth's shadow]]. This [[backscatter]]ed light produces a pinkish band opposite of the Sun's direction, called the [[Belt of Venus]].<ref name="Powell 2018 pp. 105–130">{{cite book | last=Powell | first=Jonathan | title=The Patrick Moore Practical Astronomy Series | chapter=Atmospheric Factors and Features | publisher=Springer International Publishing | publication-place=Cham | year=2018 | isbn=978-3-319-97700-3 | issn=1431-9756 | doi=10.1007/978-3-319-97701-0_8 | pages=105–130}}</ref>

===Direct sunlight===
Alpenglow in a looser sense may refer to any illumination by the rosy or reddish light of the setting or rising Sun.<ref name=DigitalPhotographySchool>{{Cite news|url=https://digital-photography-school.com/what-is-alpenglow/|title=What Is Alpenglow?|date=2012-11-01|work=Digital Photography School|access-date=2018-01-10|language=en-US}}</ref><ref>{{Cite dictionary |url=http://www.lexico.com/definition/alpenglow |archive-url=https://web.archive.org/web/20210905100046/https://www.lexico.com/definition/alpenglow |url-status=dead |archive-date=2021-09-05 |title=alpenglow |dictionary=[[Lexico]] UK English Dictionary |publisher=[[Oxford University Press]]}}</ref>

==See also==
* [[Golden hour (photography)]]

== References ==
{{Reflist}}
{{Commons}}

[[Category:Atmospheric optical phenomena]]

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