Anthelion

Anthelion

An anthelion (plural anthelia, from late Greek ανθηλιος, "opposite the sun") is a rare optical phenomenon appearing on the parhelic circle opposite to the sun as a faint white halo, not unlike a sundog.

How anthelions are formed is disputed. Walter Tape, among others, has argued they are not separate haloes, but simply where various haloes caused by horizontally oriented column-shaped ice crystals coincide on the parhelic circle to create a bright spot. If this theory is correct, anthelia should only appear together with these other haloes.cite web
url = http://www.meteoros.de/arten/ee17e.htm
title = Anthelion | publisher = Arbeitskreis Meteore e.V.
accessdate = 2007-04-22 | language = English]

However, anthelia occurs unaccompanied by other plate crystal haloes, thus scientists have produced alternative explanations. The Dutch professor S.W. Visser proposed they form by two exterior light reflections in quadrangular prisms, while Robert Greenler has suggested two interior reflection in column-shaped crystals produces the phenomenon.

While the anthelion area is usually sparse on haloes, in a complex display it features various rare optic phenomena: Flanking the anthelion on the parhelic circle are two 120° parhelia (and two Liljequist parhelia) caused by plate crystals. The Tricker and diffuse arcs are produced in singly oriented column crystals and form a Ankh-like shape passing through the anthelion. Wegener arcs occasionally crosses the sky to converge in the anthelion.cite web
url = http://www.atoptics.co.uk/halo/spanti.htm
title = South Pole Halos - Anthelic View
author = Les Cowley | publisher = Atmospheric Optics
accessdate = 2007-04-22 (including fish eye photo a.o.)]

See also

* Antisolar point
* Glory
* Liljequist parhelion
* Optical phenomenon
* Parhelion
* Rainbow
* Subparhelic circle

References

External links

* [http://epod.usra.edu/archive/epodviewer.php3?oid=301248 Earth Science Picture of the Day, April 26, 2006] - Photo of an anthelion and anthelic arcs display in Germany February 2006.


Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать реферат

Look at other dictionaries:

  • anthelion — [ant hē′lē ən, an thē′lē ən] n. pl. anthelia [ant hē′lēə, an thē′lēə] or anthelions [ModL < Gr anthēlion < anti , against + hēlios, SUN1] a rarely seen, hazy white spot at the same altitude as the sun, but opposite in the sky, caused by a… …   English World dictionary

  • Anthelion — Ant*hel ion (?; 277, 106), n.; pl. {Anthelia}. [Pref. anti + Gr. ? sun.] (Meteor.) A halo opposite the sun, consisting of a colored ring or rings around the shadow of the spectator s own head, as projected on a cloud or on an opposite fog bank.… …   The Collaborative International Dictionary of English

  • anthelion —    The term anthelion comes from the Greek words anti (against, opposite to) and helios (Sun). It translates loosely as counter Sun. The term is used in meteorology and astronomy to denote arare physical illusion consisting of a diffuse,… …   Dictionary of Hallucinations

  • anthelion — Parhelion Par*hel ion, n.; pl. {Parhelia}. [L. parelion, Gr. ?, ?; para beside + ? the sun.] A mock sun appearing in the form of a bright light, sometimes near the sun, and tinged with colors like the rainbow, and sometimes opposite to the sun.… …   The Collaborative International Dictionary of English

  • anthelion — /ant hee lee euhn, an thee /, n., pl. anthelia / lee euh/. a luminous, white spot occasionally appearing at the sun s elevation but in the opposite part of the sky. [1660 70; < LGk anthélion, neut. of anthélios opposite the sun, equiv. to ant ANT …   Universalium

  • anthelion — noun A faint, white halo rarely seen in the sky opposite the sun on the parhelic circle …   Wiktionary

  • Anthelion — Ant|he|li|on das; s, Plur. ...lia u. ...lien [...i̯ən] (meist Plur.) <aus gleichbed. gr. anthe̅lion> Gegensonne (Astron.) …   Das große Fremdwörterbuch

  • anthelion — [ant hi:lɪən, an θi:l ] noun (plural anthelia lɪə) a luminous halo round a shadow projected by the sun on to a cloud or fog bank. ↘a parhelion seen opposite the sun in the sky. Origin C17: from Gk anthēlios opposite to the sun …   English new terms dictionary

  • anthelion — ant·he·li·on …   English syllables

  • anthelion — /æntˈhiliən/ (say ant heeleeuhn), /ænˈθi / (say an thee ) noun (plural anthelia /æntˈhiliə/ (say ant heeleeuh), /ænˈθiliə/ (say an theeleeuh)) (especially in polar regions) a luminous ring seen round the shadow of the observer s head as thrown by …  

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”