Subparhelic circle

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This photo centred at the antisolar point shows various antisolar halos, as seen on a flight from Brussels to Madrid on 7 August 2006.
Credit: Francesco De Comite Subparhelic circle flickr fdecomite.jpg
This photo centred at the antisolar point shows various antisolar halos, as seen on a flight from Brussels to Madrid on 7 August 2006.
Credit: Francesco De Comité

The subparhelic circle is a rare halo, an optical phenomenon, located below the horizon. It passes through both the subsun (below the Sun) and the antisolar point (opposite to the Sun). The subparhelic circle is the subhorizon counterpart to the parhelic circle, located above the horizon.

Contents

Located on the subparhelic circle are several relatively rare optical phenomena: the subsun, the subparhelia, the 120° subparhelia, Liljequist subparhelia, the diffuse arcs, and the Parry antisolar arcs. [1] [2]

On the accompanying photo centred at the antisolar point, the subparhelic circle appears as a gently curved horizontal line intercepted by anthelic arcs. [3]

See also

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<span class="mw-page-title-main">Antisolar point</span> Point on the celestial sphere opposite Sun

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<span class="mw-page-title-main">Anthelion</span> Rare optical phenomenon

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<span class="mw-page-title-main">Circumzenithal arc</span> Optical phenomenon arising from refraction of sunlight through ice crystals

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<span class="mw-page-title-main">Parhelic circle</span> Type of halo, an optical phenomenon

A parhelic circle is a type of halo, an optical phenomenon appearing as a horizontal white line on the same altitude as the Sun, or occasionally the Moon. If complete, it stretches all around the sky, but more commonly it only appears in sections. If the halo occurs due to light from the Moon rather than the Sun, it is known as a paraselenic circle.

<span class="mw-page-title-main">120° parhelion</span>

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<span class="mw-page-title-main">Tangent arc</span> Atmospheric optical phemonenon

Tangent arcs are a type of halo, an atmospheric optical phenomenon, which appears above and below the observed Sun or Moon, tangent to the 22° halo. To produce these arcs, rod-shaped hexagonal ice crystals need to have their long axis aligned horizontally.

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A circumscribed halo is a type of halo, an optical phenomenon typically in the form of a more or less oval ring that circumscribes the circular 22° halo centred on the Sun or Moon. As the Sun rises above 70° it essentially covers the 22° halo. Like many other halos, it is slightly reddish on the inner edge, facing the Sun or Moon, and bluish on the outer edge.

<span class="mw-page-title-main">Supralateral arc</span>

A supralateral arc is a comparatively rare member of the halo family which in its complete form appears as a large, faintly rainbow-colored band in a wide arc above the sun and appearing to encircle it, at about twice the distance as the familiar 22° halo. In reality, however, the supralateral arc does not form a circle and never reaches below the sun. When present, the supralateral arc touches the circumzenithal arc from below. As in all colored halos, the arc has its red side directed towards the sun, its blue part away from it.

An infralateral arc is a rare halo, an optical phenomenon appearing similar to a rainbow under a white parhelic circle. Together with the supralateral arc they are always located outside the seldom observable 46° halo, but in contrast to supralateral arcs, infralateral arcs are always located below the parhelic circle.

<span class="mw-page-title-main">46° halo</span> Atmospheric optical phenomenon

A 46° halo is a rare atmospheric optical phenomenon that consists of a halo with an apparent radius of approximately 46° around the Sun. At solar elevations of 15–27°, 46° halos are often confused with the less rare and more colourful supralateral and infralateral arcs, which cross the parhelic circle at about 46° to the left and right of the sun.

A Liljequist parhelion is a rare halo, an optical phenomenon in the form of a brightened spot on the parhelic circle approximately 150–160° from the sun; i.e., between the position of the 120° parhelion and the anthelion.

<span class="mw-page-title-main">Parry arc</span> Optical phenomenon

A Parry arc is a rare halo, an optical phenomenon which occasionally appears over a 22° halo together with an upper tangent arc.

<i>Vädersolstavlan</i> Painting by Jacob Heinrich Elbfas

Vädersolstavlan is an oil-on-panel painting depicting a halo display, an atmospheric optical phenomenon, observed over Stockholm on 20 April 1535. It is named after the sun dogs appearing on the upper right part of the painting. While chiefly noted for being the oldest depiction of Stockholm in colour, it is arguably also the oldest Swedish landscape painting and the oldest depiction of sun dogs.

A subhelic arc is a rare halo, formed by internal reflection through ice crystals, that curves upwards from the horizon and touches the tricker arc above the anthelic point. Subhelic arcs result from ray entrance and exit through prism end faces with two intermediate internal reflections.

<span class="mw-page-title-main">Lowitz arc</span> Optical phenomenon

A Lowitz arc is an optical phenomenon that occurs in the atmosphere; specifically, it is a rare type of ice crystal halo that forms a luminous arc which extends inwards from a sun dog (parhelion) and may continue above or below the sun.

References

  1. Cowley, Les. "Subhorizon Arcs". Atmospheric Optics. Retrieved 2007-04-21. (including a computer simulation)
  2. Cowley, Les. "Antisolar Region Arcs". Atmospheric Optics. Retrieved 2007-04-21. (including a photo and a computer simulation)
  3. Moilanen, Jarmo. "Subhorizon diffuse arcs with Liljequist subparhelia". Halo Reports (Blogspot). Retrieved 2007-04-21.