Sunday, 23 July 2006

Subparhelic circle

On June/3/2006 at 20:20 CEST Susanne Danßmann observed a subparhelic circle on a flight from Berlin to Zurich. The elongated spot of light in the center of the image is likely a subanthelion. The shadow on the winglet suggests the photo was taken in direction of the antisolar point. There is no shadow of the airplane in the center of the subanthelion, because the airplane was high above the clouds.


  1. Well caught.

    Another subparhelic circle and antisolar arcs at

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  3. Very nice image!

    I think this is a left 120-degrees subparhelion instead. The sun was low, and the shadow of the trailing edge on the winglet appears to go straight down. Thus, the direction of the sun was approximately parallel to the trailing edge of the wing, which makes an angle with the direction of the bright spot on the subparhelic circle. If it were a subanthelion, the winglet would appear to be almost completely sunlit.

  4. As Mark Vornhusen points out, the phenomenon on the subparhelic circle is most likely located at subanthelic point. The missing shadow is easily explainend by the distance between the cloud and the plane. Also, really faint diffuse arc-like structure can be seen in the photo if it is processed heavily. The strongest evidence, however, can be seen in the way the wing casts a shadow on the "stabilizer" at the end of the wing. Judging from the shape of the wing it is rather safe to say that the plane where the photo is taken from is Airbus 320. Air Berlin's fleet does indeed include this type of planes. In this photo the difference in shadow shape seen from three angles is illustrated with a rough cardboard approximation of the wing. The leftmost situation is such that the Sun is directly behind the photographer. The other two photos depict such a position of the plane that the observer could be able to see a 120° subparhelion. In all photos the cardboard model is tilted so that the effective Sun altitude as seen from the imaginary cabin of our cardboard plane would be roughly equal to Susanne Danssmann photo. Comparing the results of the shadow experiment with the photo, the appearence of the shadow in the halo photo leads me to believe that the phenomenon on the subparhelic circle is indeed located at subanthelic point.