Ice Crystal Halos

Moilanen arc in Zaton, Sumava mountains

Moilanen arc in Zaton, Sumava mountains

On 3 February, Milan Osecky observed a diamond dust display with sharp Moilanen arc by the village of Zaton. The halo was seen during sunrise, when the Sun was about 4° above the horizon. The phenomenon lasted approximately 8-10 minutes, starting at 8:05 and disappearing completely by 8:15. Also a diffuse sunvex Parry arc was observed, which was a bit difficult to distinguish from the upper tangent arc due to the fuzzy border between these two arcs.

On the same day, Martin Nekola saw halos on mount Svorova in the Krkonose mountains. The photos show 22° halo, parhelia, pillars, upper tangent and infralateral arc ( 12 ).

Similarly, Tomas Trzicky in Jizerske hory observed well-defined pillars and upper tangent arcs in the light of street lamps ( 3 ).

Text: Martin Popek, Lukas Shrbeny


  • Oh boy, when will stuff like that ever be visible in southern Finland…
    The photo seems to feature a heliac arc on the left side? It’s definitely not distinguishable without unsharp masking.

  • Beautiful photo of a typical snow gun generated appearance.

    With that Parry there should be helic arc.

  • I noticed the same thing in the artificial light halo. I can also see parhelia in his photo as well.


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