2007. május 6., vasárnap

46° halo in Czech Republic

The April 21st 2007 was undoubtely one of the best halo days in this year. Observers from all over the Czech Republic enjoyed very bright 22° halo with tangent arcs and infralateral arcs.

We probably observed Wegener arcs and 120° parhelia, but this cannot be proven, because even fotos from Registax didn’t help us to clearly identify them. Anyway, Martin Popek saw that day very nice 46° halo and he took these pictures which were stacked from 40 images in Registax.

As the Sun was setting down, more halos appeared. In the second picture you can see parhelion with a part of parhelic circle (parhelic tail), 22° halo, circumzenithal arc and probably supralateral arc.

Edit: It isn’t supralateral arc in the second photo, but 46° halo because there is no upper tangent arc. That signifies absence of horizontal oriented columns, which are necessary in order to make supralateral arc.

Odd radius halos in Czech Republic

On April 5th 2007 there was typical nice, but, dry“ cirrostratus in the sky without presence of halos. I was continuously checking the sky and after 10:00 I noticed very faint halo that had unusually wide upper part. That was very suspicious to me so I started to take photos which were after processed by Registax. You can see the result in the output picture. There are two separated halos which I later identified through the comparison with night sky, as 20° and 23° halos. Maybe there is also 35° halo, but it cant be certainly identified from the picture. The phenomenon could originate at 0,3-0,0-0,0 or 1,0-0,0-0,0 crystals.

I saw very similar displays with nice, "dry" cirrostratus and then with faint odd radius halos on June 22nd 2006 and August 26th 2006 so that is quite interesting.

Martin Popek

Odd radii in Southern Finland

A horrendously quiet April passed by without any noteworthy action (except Jarmo's fantastic bolide halo). Halo people were awakened from oblivion on 5th May, when a smooth cirrostratus veil crept in from west and offered plate crystals and odd radii halos. The display was seen and photographed by Ismo Luukkonen in Turku, Marko Riikonen in Helsinki (photo on the right by Marko) and Jukka Ruoskanen in Riihimäki.

Most likely all odd radius halos were on the sky, of which 9, 18, 20 and 35 degree halos were easily discernible. The 22-24 region may have consisted of all three possible rings. Also few of the odd radius plate arcs were present, although rather poorly.