Saturday, 9 September 2006

Odd radii in Czech Republic

During the Czech halo observers meeting in Kuncice, high clouds created some good displays. This odd radius halo complex was seen on 14. August. It shows 9,° 18°, 20°, 22-24° and 35° halos. Judging from the non-uniform intensity distribution of some of the halos (9° and 20° halos being brightest on the sides), this display was caused by poorly oriented columnar pyramid crystals. It's also interesting that 20° halo is brighter than 18° halo. This type of occurrence is uncommon.

This is stacked image processed by Roman Manak and Patrik Trncak. Original photos were taken by Martin Popek.

By Marko Riikonen


  1. Column arcs? The 9 deg. halo shows possible column arc on left.

  2. Guess it could be called 9 colum arc as well (with faint 9 halo).Then we would have also 20 column arc (with faint 20 halo). It up to your taste.