Sunday, 10 May 2009

Odd radius halos from Austria

On 27th of April 2009 during the hours before noon an almost complete 23° ring was visible and also both 18° lateral arcs. All halos were visible without sunglasses. The cirrus was very dense. I know days when pyramidal halos were visible over a big area of Central Europe, but this day there are no other reported observations. The photo above shows the display with unsharp masking, but the original photo is also provided ( 1 ). Later this day only the upper part of the common 22° halo was visible.

Text: Karl Kaiser


  1. marko riikonen14 May 2009 at 09:00

    I wonder if the upper part of the 22 halo later in the day was actually 23 plate arc.

  2. Hi Marko,

    I measured the angle with my hand. I am sure
    the angle was a littel bit smaler than hours


  3. marko riikonen15 May 2009 at 21:47

    I would not trust my hand to detect that one degree difference. But I have not used much of that method.