High-altitude pyramid column arcs and kaleidoscope sky （6 May，China）

 Every year from March to May seems to be the pyramid column arcs' season for China. In the 2024 season, the most eye-catching display occured on 6 May, ChangSha, HuNan Province. At altitude of about 71.3°, the Pyramid column arcs, PC and Wegener crossed each other, bringing a spectacular picture of the sky.

(张晖)ZHANG Hui's stack image through a stack of 112 photos spanning 10 minutes. BGR and USM processes make arcs clearer.

Below are the results of a preliminary simulation using ZHANG Jia Jie 's program.

Well, now we are already looking forward to the second half of the year. Unlike March to May, June to August seems to be the peak time for pyramid plate arcs and 28° arcs for China. Please wish us luck.

JI Yun

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