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Marko Riikonen

Another Bouguer’s halo

20.12.2008 6 Marko Riikonen

These three single photos are from different stages of the 7/8 December display in Rovaniemi. They all show Bouguer’s halo, i.e. fogbow together with halos. But in reality halos and fogbow were seen mainly separately, in swiftly passing ice and…

Displays

Circular subanthelic halo from 3-5-6-7-(2)-3 raypath

16.12.2008 6 Marko Riikonen

The subhorizon photos of 7/8 December show what seems to be part of a diffuse circular halo surrounding the subanthelic point. Similar effect can be simulated with random oriented crystals (arrow in the simulation on the left). It arises from…

Displays

Blue circle

15.12.2008 7 Marko Riikonen

What happens when tilts of the crystals that make blue spot increase? The blue spot starts to elongate vertically, forming eventually a blue circle. It is shown in these images that were taken on 7/8 December night in Rovaniemi. Simulations…

Displays

A halo from Parry oriented crystals with raypath 4-8-1

11.12.2008 3 Marko Riikonen

The photo is from last weekends major display. The arrow in the accompanying simulation (Jukka Ruoskanen’s program) points to a halo that arises from Parry crystals with raypath 4-8-1 (where 3 is upper face). This arc was found from photos…

Displays

Subhorizon plate crystal halos

9.12.2008 9 Marko Riikonen

On the night of 7/8 December in Rovaniemi water fog was nucleated to diamond dust by snow machines, and a major display was observed in a spotlight beam for several hours. The photo above is from the end stage when…

Halo information

Reflected lower sunvex Parry behaviour

7.12.2008 0 Marko Riikonen

To supplement Les’s posting, here is the behaviour of the reflected Parry as a function of sun elevation. At sun elevations higher than about 11 degrees, the halo arc is below the sun. The halo is perhaps easiest understood by…

Displays

A peculiar halo on 6 November in Rovaniemi

5.12.2008 14 Marko Riikonen

In the image on the left is Moilanen arc among other halos. On the right is similar looking halo (arrow), but its V is more pointed and it is also closer to the sun, about 7 degrees above it. These…

Displays

Lascar display V

4.12.2008 1 Marko Riikonen

For the very lowest sun elevations there are only two photos, both shown here. Four uppermost images are versions of the same photo, which was the last one taken that day. Because halos have turned reddish, I suspect the sun…

Displays

Lascar display IV

3.12.2008 0 Marko Riikonen

Now the sun elevation at Lascar is 2-3 degrees. The image is four frame stack. 20° upper plate arc is well visible. New feature, “Moilanen arc”, has appeared. We observed it visually, it was V-shaped, not like the light mass…

Displays

Lascar display III

3.12.2008 4 Marko Riikonen

Continuing the Lascar halos tour. This image gives situation for sun elevation range of 11° to 9°. Image is stacked from four photos and also mirrored version is provided. 23° plate arc is already disappearing high up above the sun,…

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Author Archives

Marko Riikonen

Another Bouguer’s halo

Circular subanthelic halo from 3-5-6-7-(2)-3 raypath

Blue circle

A halo from Parry oriented crystals with raypath 4-8-1

Subhorizon plate crystal halos

Reflected lower sunvex Parry behaviour

A peculiar halo on 6 November in Rovaniemi

Lascar display V

Lascar display IV

Lascar display III

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