Attila Kosa-Kiss from Salonta, Romania observed on 29th September 2006 a very interesting halo display at a sun elevation of 12°. Unfortunately, there were no photos but there is a sketch. The most probable explanation is the existence of suncave [H] and sunvex [G] Parry arcs, as shown by the simulation from Les Cowley. Other possibilities would be an circular Lowitz arc [F], as seen on the simulation with HALOET (random: 0.5, plates: 0.5, columns: 0.5, parry: 0.5, Lowitz: 4.0, number of rays=150000). On the same day was observed several time in Germany and Czech the upper part of Lowitz arcs. But Romania was influenced by another weather front (with another cirrus clouds) like the middle European area. Further comments and ideas are very welcome!
by Claudia Hinz
What a great display must this has been!!! Suncave and sunvex Parry arcs looks the best explanation to me.
ReplyDeleteI know of one observation from The Netherlands from 16 october 1996 (source: Weerspiegel, dutch weather magazine) where almost a copy of this very rare display occured.