Parhelion: Difference between revisions
From Glossary of Meteorology
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<div class="definition"><div class="short_definition">( | <div class="definition"><div class="short_definition">(''Also called'' sun dog.) A [[halo]] in the form of a colored spot at the same angular [[elevation]] as the sun.</div><br/> <div class="paragraph">The lunar counterpart is a paraselene. The most common parhelia are seen about 22° on either side of the sun. That angular distance increases from 22° when the sun is on the [[horizon]] to over twice that when the sun climbs to 60°. The sun side of a parhelion is reddish. The parhelia of 22° can be explained by [[refraction]] in hexagonal crystals falling with principal axes vertical. The effective prism angle is 60° when the sun is on the horizon, but this increases as the sun climbs, resulting in greater displacement of the parhelion.</div><br/> </div> | ||
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Latest revision as of 15:48, 20 February 2012
parhelion
(Also called sun dog.) A halo in the form of a colored spot at the same angular elevation as the sun.
The lunar counterpart is a paraselene. The most common parhelia are seen about 22° on either side of the sun. That angular distance increases from 22° when the sun is on the horizon to over twice that when the sun climbs to 60°. The sun side of a parhelion is reddish. The parhelia of 22° can be explained by refraction in hexagonal crystals falling with principal axes vertical. The effective prism angle is 60° when the sun is on the horizon, but this increases as the sun climbs, resulting in greater displacement of the parhelion.