Saturday, 30 August 2008

High-sun parry arc in Ohio USA 8-22-08

For the first time since April 10th I have gotten some photoworthy halos. In all I got 22° halo complete circumscribed halo, complete parhelic circle, circumhorizontal arc, and my first high-sun parry ( 1 - 2 ). I saw reports of high-sun parry a couple days before on the blog but when I spotted a faint but clearly visible arc separate from the top of the circumscribed halo I knew that I was looking at a high-sun parry. While taking photos I searched carefully for lower suncave parry arc but it was not to be found. So the concentration of parry falling crystals was small. While I was unloading groceries from my mother's truck I held very still and took a bunch of photos to make a stack set which I stacked that day. I also did a simulation with HaloSim and using the gap between upper parry and the circumscribed halo as a reference the elevation was 61 degrees( 3 ).

Wednesday, 27 August 2008

Report of the Czech 'Halo Observe Project' (HOP) about the past three months

Photographs above by Patrik Trncak and Martin Popek.

16th June 2008 - 120° parhelion

Tomas Trzicky observed a 120° parhelion during a flight over the Czech Republic. It was seen only briefly somewhere over the western part of the country while flying through cirrus clouds ( 1 ).

17th June 2008 - Elliptical halo in Holesov

Patrik Trncak, who observed the phenomenon in Holesov wrote: "It lasted a short time, a couple of seconds. The ellipse was complete, but the bottom quickly disappeared. It was observed on Ac virga, and irridescent clouds were seen, too." ( 2 )

20th June 2008 – Sunvex Parry arc in Prague

Monika Pacltova, who observed the phenomenon in the centre of Prague (Karlov) wrote: "Late afternoon I decided to make a time lapse video of the sunset with a 22° halo, bright parhelia and nice upper tangent arc. But... oh, damn! This simple and well-arranged display was all of a sudden 'badly spoilt' by a strange smudge above. Yeah, I saw the first Parry sunvex in my life". ( 3 - 4 - 5 )

24th June 2008 - Pyramidal halos in Prague

Stepanka Kosova observed in Prague-Uhrineves relatively strong 9° halo. Stacking a few pictures has shown other possible odd radius halos as well ( 6 - 7 - 8 ).

3rd August 2008 – Bottlinger's ring during a Prague-Moscow flight

Martin Popek wrote: "In the middle of the journey I observed a clear subsun. It was in a very low position almost beneath the plane. Nevertheless, I succesfully photographed a series of pictures which I stacked in Registax. Then the elliptical figure, similar to Bootlinger's ring was visible. By naked eye the phenomenon was seen as a veil around subsun. The phenomenon was observed on cloud type Ac translucidus perlucidus." ( 9 )

11th August 2008 – Suncave Parry arc and 120° parhelion in Morava

A number of observers saw a quite clear suncave Parry arc in the Czech Republic. This followed the previous observation of Parry arcs in Germany by the same cloud front. Martin Popek photographed 50 pictures, stacked in Registax ( 10 ). The suncave Parry arc was observed by Jan Kondziolka in Karvina as well ( 11 ). Martin Jankovic saw a nice 120° parhelion in Brno ( 12 ).

15-17th August 2008 – Halo meeting in Holesov

After two years, halo-phenomena observers in the Czech Republic held a meeting again. This time it was organised by Patrik Trncak in Holesov. Ten observers arrived during the weekend, and although the weather was not too favourable for halo observation, we spent the time successfully: we had lectures on rare halo phenomena and Registax, slide shows and consultations about photo-editing and the future of the Czech HOP project. Here are some photos at and the magazine Parhelium ( 13 - 14 ).

Text: Martin Popek, Monika Pacltova

Thursday, 21 August 2008

Two high-sun Parry arcs

We tend to think of upper Parry arcs the way we see them at low sun. Two observations from the past months, however, show what they look like when the sun is high up in the sky.

In the above image, we can see an almost straight-looking Parry arc photographed by Faber McMullen at 69° sun altitude. The image was taken in Navasota, Texas, on 8 May 2008. The Parry arc was accompanied by a circumscribed halo, and a parhelic circle that is faintly present in the pictures, too ( 1 ). He also made a simulation with Les Cowley’s and Michael Schroeder’s HaloSim, which helps to interpret the photo ( 2 ).

The other observation comes from Holesov, Czech Republic. Patrik Trncak photographed a short-lived Parry arc at 61° sun altitude on 19 June ( 3 ). The circumstances were similar. The cirrus clouds produced a circumscribed halo and a full parhelic circle besides the Parry arc.