Focus on Vädersolstavlan and discuss the Halo display.
While the painting is arguably the oldest realistic depiction of a halo phenomenon — almost a century older than Christoph Scheiner's famous observation of a halo display over Rome in 1630 — the phenomenon was apparently not entirely understood. The image contains several obvious misinterpretations and a few peculiarities.  Most notably, like many other early depictions of haloes, the painting depicts a series of events occurring over several hours and is consistent in its preference for perfect circles rather than ellipses.A work of art produced in the spirit of the Danube School (see Possible prototypes above), Vädersolstavlan features realistic depictions of cirrus clouds and the sky is properly rendered, going from bright blue near the horizon to dark blue near zenith. The shadows in the lower half of the painting, however, seem to suggest the Sun is located in the west — even leaving the southern façades in shadow — which is incorrect as historical sources claim the event lasted from 7 to 9 a.m.  In contrast to the city below it, the halo phenomenon is depicted vertically in a fisheye perspective with the major circle centred on zenith (like in the ray tracing solution above).In the painting, the actual Sun is the yellow ball in the upper-right corner surrounded by the second circle.  The large circle taking up most of the sky is a parhelic circle, parallel to the horizon and located at the same altitude as the Sun, as the painting renders it.  This is actually a common halo, although a full circle as depicted is rare.  Such parhelic circles are caused by horizontally oriented plate ice crystals reflecting sun rays.  In order for a full circle to appear sun rays must be reflected both internally and externally.
The circle surrounding the Sun is a 22° halo, as the name implies located 22° from the Sun.  While the painting depict it pretty much as it normally appears, it should be centred on the Sun and is misplaced in the painting.
The pair of arcs flanking the 22° halo and crossing each other are most likely a misinterpretation of a circumscribed halo.  While the Sun is still low, it starts as a V-shaped upper tangent arc which gradually develops into something looking like the unfolding wings of a seagull. As the Sun ascends, in rare cases it finally joins with the lower tangent arc to form an ellipse which closes in on the circumscribed 22° halo.The sun dogs or parhelia, in the painting erroneously pinned to the misinterpreted arcs of the circumscribed halo, are rather frequent optical phenomena which appear when sunlight is refracted by hexagonal ice crystals forming cirrus or cirrostratus clouds.  When the Sun is still low, they are located on the 22° halo, the way they are most commonly observed, and as the Sun ascends they move laterally away from the 22° halo.  At rare occasions, they can actually reach the circumscribed halo.  As depicted in the painting, the sun dogs are located midway between the 22° halo and the circumscribed halo, and, assuming they are correctly rendered, the Sun should have been located at about 35–40° above the horizon (as in the simulation above).The unintelligible arc on the lower right might be a misinterpreted and misplaced infralateral arc missing its mirrored twin.  These phenomena are, however, rare and only form when the Sun is below 32°. Their shape change quickly as the Sun rises, and as the painting most likely isn't depicting any specific moment, it is impossible to draw any conclusions from the mysterious shape in the painting.
The crescent moon shape in the middle of the sky looks very much like a circumzenithal arc, which is parallel to the horizon but centred at and located near zenith.  However, they only form when the Sun is located lower than 32.2° and are at their brightest when the Sun is located at 22°, which is not consistent with other haloes depicted in the painting.  Furthermore, one of the most striking features of circumzenithal arcs is their rainbow colours, and the shape in the painting is perfectly devoid of any colours. It is however not a complete circle (see Kern arc), and it is facing the Sun, which are both correct properties for this phenomenon.The white spot on the lower left part of the parhelic circle, opposite to the Sun, should be an anthelion, a bright halo always located at the antisolar point.  Most scientists are convinced anthelia are caused by the convergence of several halo arcs (of which are no traces in the painting) and thus should not be regarded as an independent halo.  Other researchers believe column-shaped crystals could generate the phenomenon which could explain the constellation in the painting.Finally, the minor, slightly bluish dots, flanking the anthelion, may be perfectly depicted 120° parhelia. These halos are produced by the same horizontally oriented ice crystals that produce sun dogs and the parhelic circle.  They result from multiple interior reflections of sun rays entering the hexagonal top face and leaving through the bottom face.
ice crystal infralateral arc antisolar point painting lower tangent arc Kern arc upper tangent arc Sun cirrostratus cloud circumzenithal arc sun dog zenith 120° parhelia hexagon fisheye horizon parhelic circle cirrus refracted Christoph Scheiner anthelion right cirrus cloud Possible prototypes circumscribed halo halo phenomenon 22° halo left halo