Aureoles on April 6th, 2010
Diffracting aerosols often form faint aureoles with a bluish centre and a brownish ring rather than multi-ringed colourful coronae around the sun. In this case the diffracting particles may have been water droplets, small ice crystals, dust or pollen - possibly willow, alder or the first birch pollens. These aureoles were not produced by volcanic ashes as there was absolutely no activity at this time.
Links to related articles: