Tuesday, 6 March 2007

Odd radius halos in diamond dust in Finland

On 23 February an another diamond dust display with odd radius halos occured in Vaala, Finland. Temperature was dropping from -29°C to -24° during my observation.

A parhelic circle and circumzenithal arc were present with nice parhelia. A subsun and subparhelia were also seen as sparkling ice crystals in front of the ground.

Odd radius halos labelled in this enhanced photo are A) a pyramidal heliac arc, B1) upper 24° plate arc, B2) lower 24° plate arc and C) upper 23° plate arc.

The most brightest odd radius halo was 18° halo and in some photos there probably are also 9° upper plate arc and 20° halo. The ice crystal cloud was produced by a local heating plant about 2 km away. More photos can be found here.

By Jarmo Moilanen


  1. Did you get any crystal samples?

  2. Unfortunately not.

    I did all these diamond dust observations in February during my working day. I do not have any good way to keep my crystal sampling equipments with me during my work hours. I need to get that problem solved. This was a really interesting oppornity to get crystal samples. I missed it now.

  3. Well as they say there is always a next time.