Circumzenithal Arc (Sep 2, 2001)


Date & Time: Sep 2 2001, 16:28 JST(+0900), 1/600sec. Exp.
Optical: f=10.4mm F8.0 (equivalent f=70mm in 35mm film format)
Digital Camera: CASIO QV-2800UX
Location: Kokubunji city, Tokyo

Camera Settings: Mode...1600×1200 FINE
CCD sensitivity...ISO80, White Balance...Daylight



   This picture shows you relative position of Circumzenithal Arc to the sun by the mosaic of two shots. You can see the Arc in upper part and the sun is positioned beyond a tree in lower part.
  They're lying about 46 degrees apart. And this image shows you fairly indistinct solar halo between the Circumzenithal Arc and the sun.


Date & Time: Sep 2 2001, 16:29 JST(+0900), 1/800sec. Exp.
Optical: f=6.6mm F4.8 (equivalent f=43mm in 35mm film format)
Digital Camera: CASIO QV-2800UX
Location: Kokubunji city, Tokyo

Camera Settings: Mode...1600×1200 FINE
CCD sensitivity...ISO80, White Balance...Daylight


Schematics of Circumzenithal Arc
Upper: Schematic of ice crystal
Lower: Sunlight path through ice crystal
  A rainbow-like light appeared in zenith sky when the sun was sinking in the west. This rare atmospheric phenomenon, called "Circumzenithal Arc", can be observed by the refracted solar light through the hexagonal ice crystals. The principle is almost same with the Circumhorizontal Arc written in previous page.
Circumzenithal Arc can be seen at about 46 degrees upper than the sun because the refraction angle by ice crystal is about 46 degrees.   In that day, I could observe beautiful spectrum colors with naked eyes, and disappeared about 30 minutes later.



Circumhorizontal Arc (Apr 22, 2001)
Rainbow

Copyright(c) 2001 by Naoyuki Kurita, All rights reserved.
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