OPOD - Aureoles large and small

Aureoles Small & Large

Top: Venus in the Pleiades surrounded by a blue centred and red fringed aureole ~0.4° radius produced by small water droplets. Image by Maximilian Teodorescu (site) in Dumitrana, Romania 3rd April '12.

Lower: A huge aureole around the sun produced in Hungary by sand carried from Africa. Imaged by Monika Landy-Gyebnar.

"On 5th April we had much African dust above Hungary, very early this year... I noticed it late in the morning and the diameter of the dusty disk around Sun was 18-20° radius at maximum size. Usually these African dusty airmasses come here from late April to late June, so this appearance is really early."

Images ©Maximilian Teodorescu and Monika Landy-Gyebnar

Droplets, sand, pollen, pigs with wings - all can produce aureoles. The larger the object the smaller is the aureole.

Light is scattered mostly from the periphery of the objects. When they are all more or less equal sized the central aureole is surrounded by coloured rings - a corona = otherwise we see only the aureole which may not even be red fringed.

An aureole is always present around the sun unless the air is exceptionally free of dust and aerosol.