Ice Crystal Halos

Subhelic arc in Finland

A halo display was observed on 28 May 2008 in Oulu, Finland. It was reported even by local newspaper Kaleva and some photos sent by readers were published – see 29.5.2008 photos ( 1 ). According to those photos, the display did have a very strong and colorful supralateral arc with great circumzenith arc in the earlier stage.

First photos were reported an hour earlier than I noticed the display. When I was outside the display was not very bright anymore ( 2 ).

Soon a faint white arc got my attention at atzimut around 100 degrees and high above horizon. It was first faint and hard to see and it also disappeared for a moment. Toward the end of the display, the arc got better intensity and lenght. The halo was a subhelic arc from column oriented ice crystals. An arc located this way could be also be a heliac arc, but no halos related to Parry orientation was seen. Subhelic arc was already visible as a faint and short arc in some photos which I took before I noticed the arc.


  • Nice catch Jarmo! The sky here is blank with the exception of common halos but nothing rare.

    Did you hear about my two hour long elliptical halo display?


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