Saturday, 6 January 2007

Moon halo over Southern Finland - oriented columns in command



Little after midnight on the night of 5-6th January a fairly bright 22 halo and upper tangent arc appeared in high clouds. At this stage nothing implied that anything better would be on the way. However, at around 1.30 a.m. the halos arising from oriented columns had got much better and upper and lower tangent arcs stretched out to form a circumscribed halo. Infralateral arcs and a 9 halo appeared as well. Judging from the quality of circumscribed halo and infralateral arcs at the maximum phase one might suspect that rays scattered by oriented columns may have partially contributed to the intensity of the 9 halo.

The display ended at around 4 a.m. when low level clouds rolled in. Shortly before that 46 halo and parhelic circle were well formed (although faint). According to the reports so far the display was best seen in Tampere (photos by Jari Luomanen) and in Riihimaki (photos by Jukka Ruoskanen) .

2 comments:

  1. Jukka's 060107_klo0300_18stack_8mm.jpg
    is perhaps the best photo of 46° halo that I recall.

    The combination of bright 22° halo and faint but full circumscribed halo looks weird. Never seen anything quite like that.

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  2. This display gave me my first 9 degree halo. Otherwise there wasn't anything else visible than the 22 halo and a faint upper tangent arc.

    Pics by Luomanen and Ruoskanen are, again, very nice.

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