Getting ready for the diamond dust

Getting ready for the snowgun season. One searchlight, 25ah battery power, dslr cam + fisheye lens and a tripod. A total of 15 kilos to carry around. If I had a microscope to sample the ice crystals I would carry that as well. I keep my fingers crossed and hope that despite current economical situation the majority of the ski centers in Estonia that have the guns start snowgunning as soon as the temperatures allow it.

Edit 15.12: Looks like most of the guns are operating now...now just waiting favorable weather conditions.

Edit 17.12 Medium wind speed and humidity around 75-82%. Not good for diamond dust.
At the same time Finnish guys have been lucky: Marko Mikkilä 14.12 display, Jukka Ruoskanen 14.12 dislay. J.Ruoskanen has been very lucky: first 18° and 35° halos in diamond dust with artificial light source. So it's first time we see odd radii halos from snowguns. According to M.Riikonen it's obvious that snow guns can make pyramidial crystals but generally it's difficult to get an odd radii diamond dust because very low temperatures are needed for major pyramidial crystal development.

Edit: 19.12 After five days of consecutive snowgunning the guns have been stopped in most of the ski centers. The snowgun season is over.

44 degree parhelion in Estonia

On 3rd of Januray it was possible in South-Estonia, Tartu to observe bright halo what was photographed by many people and was later reflected by media. Afterwards I was browsing the news on ilm.ee and noticed that there might be 44° parhelion on picture taken by Aavo Omann. After closer inspection and browsing other captures it was clear that indeed it was 44° parhelion because there were no signs of 46° latereal arcs and the 22° upper tangent arc was weak.
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3.jaanuaril oli Lõuna-Eesti taevas võimalik vaadelda erakordselt eredat halo, mida paljud ka pildistasid ning meediaväljaanded kajastasid. Vaatasin ilm.ee uudiseid ja tekkis kahtlus, et fotodel võib olla jäädvustatud 44° parheelion. Selgus, et nähtuse, mida on fotodokumenteeritud eelnevalt kümnel korral, on sedakorda jäädvustanud Aavo Omann. Kuna piltidel suure halo külgmised kaared puuduvad ja väikese halo puutujakaared on väga nõrgad, siis sellest võib järeldada, et tegemist on 44° parheelioniga.

Esmapilgul võivad nad vaatlejale paista kui 46° halo/või selle puutujakaare osad, kuid nad ei ole seda, sest ligem vaatlus ja täpne mõõtmine näitab, et nad on päikesele ligemal.

44° parheelionid on näide valguse mitmekordsest hajumisest. Lihtsamalt öeldes on nad "päikesekoerte päikesekoerad", tekitatud valguskiirte poolt, mille teekond on juba läbinud plaadikujulise kristalli (mis muidu oleks tekitanud 22° päikesekoera), kuid omakorda kinni püütud teise plaatkristalli poolt ja alles siis kõrvale kaldunud. Topeltkõrvalekalde puhul on minimaalne kõrvalkalde nurk 44°. Plaatkristallide kontsentratsioon õhus peab olema väga suur.

Teadaolevad fotodokumenteeritud juhud:
3 Dets 1970, Saskatoon, Kanada, Earle Ripley
23 Jan 2002, Vaala, Soome, Jarmo Moilanen (1 2) visand
Juuni 2002, Gröönimaa, Matthew Hyde (1)
30 Dets 2002, Juva, Soome, Jari Piikki (1) visand
3 Jan 2004, Minnesota, USA (1)
21 Nov 2004, Teuva, Soome, Heikki Mahlamäki (1 2 3 4 5)
21 Dets 2005, Viitasaari, Soome, Jaakko Tähti (1 2)
3 Jan 2006, Stockholm, Rootsi, Yvonne Primé (1)
17 Nov 2008, Sotkamo, Soome, Marko Mikkilä (1)
2 Jan 2009, Tampere, Soome, Jari Luomanen (1 2 3 4)
19 Veeb 2009, Fargo, ND., USA, Jordan Hofker (1)

Exciting new halo forms from Rovaniemi

November and December - the best time in year to travel Rovaniemi where the snow machines are in constant run generating the nuclei that helps to form the diamond dust.

6th November '08 - A new halo seen and photographed by Marko Riikonen. A new arc generated quite an excitement and discussion among the halo experts. Later the new halo explained by Walter Tape as the reflected lower sunvex Parry arc.
You can read more about it from ICH site - here and here. A detailed explanation is available on Atmospheric Optics.

7th December '08 - even more new halos by Marko Riikonen! In this time the new subhorizon halos: sub-120° parhelion, sub-Kern and subcircumnadiral arc formed by plate crystals. Also take a look on ICH site where Marko riikonen presenting the anthelion view of this display.