A 120° parhelion (plural: 120° parhelia) is a relatively rare

halo Halo, halos or haloes usually refer to: * Halo (optical phenomenon) * Halo (religious iconography), a ring of light around the image of a head HALO, halo, halos or haloes may also refer to: Arts and entertainment Video games * Halo (franchise), ...

, an

optical phenomenon Optical phenomena are any observable events that result from the interaction of light and matter. All optical phenomena coincide with quantum phenomena. Common optical phenomena are often due to the interaction of light from the sun or moon wit ...

occasionally appearing along with very bright

sun dog A sun dog (or sundog) or mock sun, also called a parhelion (plural parhelia) in meteorology, is an atmospheric optical phenomenon that consists of a bright spot to one or both sides of the Sun. Two sun dogs often flank the Sun within a 22° ...

s (also called parhelia) when

ice crystal Ice crystals are solid ice exhibiting atomic ordering on various length scales and include hexagonal columns, hexagonal plates, dendritic crystals, and diamond dust. Formation The hugely symmetric shapes are due to depositional growth, na ...

-saturated

cirrus cloud Cirrus ( cloud classification symbol: Ci) is a genus of high cloud made of ice crystals. Cirrus clouds typically appear delicate and wispy with white strands. Cirrus are usually formed when warm, dry air rises, causing water vapor deposition on ...

s fill the atmosphere. The 120° parhelia are named for appearing in pair on the

parhelic circle 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. ...

±120° from the sun. (including a HaloSim simulation.) When visible, 120° parhelia appear as white-bluish bright spots on the white parhelic circle and are the product of at least two interior reflections in the

hexagon In geometry, a hexagon (from Greek , , meaning "six", and , , meaning "corner, angle") is a six-sided polygon. The total of the internal angles of any simple (non-self-intersecting) hexagon is 720°. Regular hexagon A ''regular hexagon'' h ...

al ice crystals. Their colour together with them being rather obscure can make observing them difficult as they tend to fuse with the clouds in the sky.

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A photo of a 120° parhelion in the Czech Republic in October 2006

A photo by Joni Tornambe, 2006

A video from Russia featuring both 120° parhelia, as well as the classic sundogs and parhelic circle, 2007

A similar video from Kazakhstan with very bright 120° parhelia, 2007
Warning: loud audio! {{DEFAULTSORT:120 parhelion Atmospheric optical phenomena fr:Parhélie#Paranthélies et parhélies secondaires

See also

References

External links