Antitwilight arch

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<div class="definition"><div class="short_definition">A bright wedge of pink, orange, or [[purple light]] that extends around the antisolar  [[horizon]] during [[clear]] twilights and that has the greatest vertical width (&sim;3&deg;&ndash;6&deg;) occurring above  the [[antisolar point]].</div><br/> <div class="paragraph">The antitwilight arch rises with the antisolar point at [[sunset]] and sets with the antisolar point  at [[sunrise]]. The antitwilight arch is brighter than the bluish gray [[dark segment]] beneath it. The  boundary between these features may be distinct shortly after sunset (sun [[elevation]] ''h''<sub>0</sub> &sim; &minus;2&deg;),  but it fades as evening [[twilight]] progresses.</div><br/> </div>
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<div class="definition"><div class="short_definition">A bright wedge of pink, orange, or [[purple light]] that extends around the antisolar  [[horizon]] during [[clear]] twilights and that has the greatest vertical width (&sim;3&#x000b0;&ndash;6&#x000b0;) occurring above  the [[antisolar point]].</div><br/> <div class="paragraph">The antitwilight arch rises with the antisolar point at [[sunset]] and sets with the antisolar point  at [[sunrise]]. The antitwilight arch is brighter than the bluish gray [[dark segment]] beneath it. The  boundary between these features may be distinct shortly after sunset (sun [[elevation]] ''h''<sub>0</sub> &sim; -2&#x000b0;),  but it fades as evening [[twilight]] progresses.</div><br/> </div>
 
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Latest revision as of 16:39, 20 February 2012


[edit] antitwilight arch

A bright wedge of pink, orange, or purple light that extends around the antisolar horizon during clear twilights and that has the greatest vertical width (∼3°–6°) occurring above the antisolar point.

The antitwilight arch rises with the antisolar point at sunset and sets with the antisolar point at sunrise. The antitwilight arch is brighter than the bluish gray dark segment beneath it. The boundary between these features may be distinct shortly after sunset (sun elevation h0 ∼ -2°), but it fades as evening twilight progresses.

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