Editing Afterglow

{{Short description|Whitish or rosy light during twilight or after sunset}}
{{other uses}}
[[File:Abenddämmerung mit Purpurlicht und Schattenstrahlen.jpg|thumb|Afterglow with its bright segment and purple light above, interrupted by [[crepuscular rays]]]]

An '''afterglow''' in [[meteorology]] consists of several [[Optical phenomena#Atmospheric optical phenomena|atmospheric optical phenomena]], with a general definition as a broad arch of whitish or pinkish [[sunlight]] in the [[twilight]] [[sky]], consisting of the '''bright segment''' and the '''purple light'''.<ref name="ametsoc">{{cite web |title=afterglow |website=AMS Glossary |publisher=[[American Meteorological Society]] |date=2015-10-05 |url=https://glossary.ametsoc.org/wiki/Afterglow |archive-url=https://web.archive.org/web/20151005210202/https://glossary.ametsoc.org/wiki/Afterglow |archive-date=2015-10-05 |url-status=dead |access-date=2022-08-14}}</ref><ref name="Glossary">{{cite web |publisher=The Formula |title=Full text of 'Weather Glossary' |website=Internet Archive |date=2022-01-14 |url=https://archive.org/stream/in.ernet.dli.2015.217458/2015.217458.Weather-Glossary_djvu.txt |access-date=2022-08-14}}</ref> Purple light mainly occurs when the Sun is 2–6° below the [[horizon]], from [[civil twilight|civil]] to [[nautical twilight]], while the bright segment lasts until the end of the nautical twilight.<ref name="ametsoc-purple">{{cite web |title=purple light |website=AMS Glossary |publisher=[[American Meteorological Society]] |url=https://glossary.ametsoc.org/wiki/Purple_light |access-date=2022-08-14}}</ref><ref name="ametsoc-bright">{{cite web |title=bright segment |website=AMS Glossary |publisher=[[American Meteorological Society]] |url=https://glossary.ametsoc.org/wiki/Bright_segment |access-date=2022-08-14}}</ref> Afterglow is often in cases of [[volcanic eruption]]s discussed,<ref name="Corfidi">{{cite web |title=The Colors of Twilight and Sunset |first= Stephen F.|last=Corfidi |publisher=[[NOAA]]/[[National Weather Service|NWS]] [[Storm Prediction Center]] |url=https://spc.noaa.gov/publications/corfidi/sunset |access-date=2022-08-14}}</ref> while its purple light is discussed as a different particular ''volcanic purple light''.<ref name="Purple">{{cite journal | last1=Lee | first1=Raymond L. | last2=Hernández-Andrés | first2=Javier | title=Measuring and modeling twilight's purple light | journal=Applied Optics | publisher=The Optical Society | volume=42 | issue=3 | date=2003-01-20 | pages=445–457 | issn=0003-6935 | doi=10.1364/ao.42.000445 | pmid=12570266 | bibcode=2003ApOpt..42..445L }}</ref> Specifically in volcanic occurrences it is [[light scattering|light scattered]] by fine [[particulates]], like [[dust]], suspended in the [[Earth's atmosphere|atmosphere]].<ref name="Purple"/> In the case of [[alpenglow]], which is similar to 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=978-3319977003 | issn=1431-9756 | doi=10.1007/978-3-319-97701-0_8 | pages=105–130}}</ref> afterglow is used in general for the golden-red glowing light from the [[sunset]] and [[sunrise]] reflected in the sky, and in particularly for its last stage, when the purple light is reflected.<ref name="Glossary"/><ref name="ametsoc"/> The opposite of an afterglow is a '''foreglow''', which occurs before [[sunrise]].

Sunlight reaches Earth around civil twilight during [[Golden hour (photography)|golden hour]] intensely in its [[energy of light|low-energy]] and low-frequency red [[Electromagnetic spectrum#Visible radiation (light)|component]].
During this part of civil twilight after sunset and before sundawn the red sunlight remains visible by [[scattering]] through particles in the air. [[Backscatter]]ing, possibly after being [[reflection (optics)|reflected]] off [[cloud]]s or high [[Snow field|snowfields]] in [[mountain]] regions, furthermore creates a reddish to pinkish light. The high-energy and [[high-frequency]] components of light towards blue are [[scattering of electromagnetic radiation|scattered]] out broadly, producing the broader blue light of nautical twilight before or after the reddish light of civil twilight, while in combination with the reddish light producing the purple light.<ref name="Corfidi"/> This period of blue dominating is referred to as the [[blue hour]] and is, like the golden hour, widely treasured by photographers and painters.

After the [[1883 eruption of Krakatoa|1883 eruption]] of the [[volcano]] [[Krakatoa]], a remarkable series of red [[sunset]]s appeared worldwide. An enormous amount of exceedingly fine dust were blown to a great height by the volcano's explosion, and then globally diffused by the high atmospheric winds. [[Edvard Munch]]'s painting ''[[The Scream]]'' possibly depicts an afterglow during this period.

<gallery class="center">
File:Dämmerung mit Purpurlicht und Schattenstrahlen, 10.10.2011 bei Limburg VIII.jpg|Purple light with crepuscular shadow
File:Lamma evening4.jpg|Sunset in Hong Kong after the [[1991 eruption of Mount Pinatubo]]
File:Dresden.afterglow.700px.jpg|An afterglow in [[Dresden]], [[Saxony]], [[Germany]]
File:Afterglow.jpg|An afterglow in [[Slovenia]]n mountains, near [[Triglav Lakes Valley]]
File:Full Image Sunset Bates College Lewiston Maine July 3 2008 8.30PM.JPG|Sunset over the [[Bates College]] [[Track and field|track]] in [[Lewiston, Maine]]
File:Noarlunga Pier, Adelaide.jpg|An afterglow at a pier in [[Australia]]
File:Afterglow in Sanchong, New Taipei 20140114.jpg|An afterglow on skyscrapers in [[New Taipei]], [[Taiwan]]
File:Afterglow Kraków.JPG|An afterglow on a [[Kraków]] housing estate
File:Optical effect march sunset - NOAA.jpg|Additional to foreglow here [[refraction|refracted]] sunlight reaches the [[South Pole]] just before actual sunrise. At [[Earth's poles]] the Sun appears at the horizon only and all day around [[equinox]], marking the change between the half year long [[polar night]] and [[polar day]].
</gallery>

==See also==
* [[Airglow]]
* [[Belt of Venus]]
* [[Earth's shadow]]
* [[Gegenschein]]
* [[Red sky at morning]]
* [[Sunset]]

==References==
{{Reflist}}

==External links==
{{Commons category}}
{{EB1911 poster|Afterglow}}
{{wiktionary}}

[[Category:Atmospheric optical phenomena]]

[[es:Arrebol]]
[[fi:Purppuravalo]]