by APOD Robot » Mon Aug 30, 2021 4:06 am
A Fire Rainbow over West Virginia
Explanation: What's happening to this cloud? Ice crystals in a distant cirrus cloud are acting like little floating
prisms. Known informally as a fire rainbow for its flame-like appearance, a
circumhorizon arc appears parallel to the horizon. For a
circumhorizontal arc to be visible,
the Sun must be at least 58 degrees high in a sky where
cirrus clouds present below -- in this case
cirrus fibrates. The numerous, flat,
hexagonal ice-crystals that compose the
cirrus cloud must be
aligned horizontally to properly
refract sunlight in a collectively similar manner. Therefore,
circumhorizontal arcs are
somewhat unusual to see. The
featured fire rainbow was photographed earlier this month near
North Fork Mountain in
West Virginia,
USA.
[url=https://apod.nasa.gov/apod/ap210830.html] [img]https://apod.nasa.gov/apod/calendar/S_210830.jpg[/img] [size=150]A Fire Rainbow over West Virginia[/size][/url]
[b] Explanation: [/b] What's happening to this cloud? Ice crystals in a distant cirrus cloud are acting like little floating [url=http://micro.magnet.fsu.edu/primer/java/scienceopticsu/newton/]prisms[/url]. Known informally as a fire rainbow for its flame-like appearance, a [url=https://en.wikipedia.org/wiki/Circumhorizon_arc]circumhorizon arc[/url] appears parallel to the horizon. For a [url=https://www.atoptics.co.uk/halo/cha2.htm]circumhorizontal arc[/url] to be visible, [url=https://solarsystem.nasa.gov/solar-system/sun/overview/]the Sun[/url] must be at least 58 degrees high in a sky where [url=https://en.wikipedia.org/wiki/Cirrus_cloud]cirrus clouds[/url] present below -- in this case [url=https://www.colweather.org.uk/gal-clouds-cirrus.php#Cirrus%20fibratus]cirrus fibrates[/url]. The numerous, flat, [url=http://www.atoptics.co.uk/halo/orplate.htm]hexagonal ice-crystals[/url] that compose the [url=https://en.wikipedia.org/wiki/Cirrus_cloud]cirrus cloud[/url] must be [url=https://www.atoptics.co.uk/halo/platcol.htm]aligned horizontally[/url] to properly [url=http://youtube.com/watch?v=U98KPM2b9IA]refract sunlight[/url] in a collectively similar manner. Therefore, [url=https://apod.nasa.gov/apod/ap190519.html]circumhorizontal[/url] [url=https://apod.nasa.gov/apod/ap151215.html]arcs[/url] are [url=https://i.pinimg.com/550x/81/21/c0/8121c0291fa14d1fe52b9eb007741cac.jpg]somewhat unusual[/url] to see. The [url=https://www.facebook.com/photo?fbid=4794142133932422]featured fire rainbow[/url] was photographed earlier this month near [url=https://youtu.be/kROh8JwKnOk]North Fork Mountain[/url] in [url=https://en.wikipedia.org/wiki/West_Virginia]West Virginia[/url], [url=https://en.wikipedia.org/wiki/United_States]USA[/url].
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