|Here the sun is not eclipsed by the wing and its light dazzles the camera CCD and scatters from window scratches.|
|The aureole is normally a few degrees in diameter, its apparent size depending on the size and concentration of atmospheric dust and aerosol.
The scattering particles diffract incident light to direct it forward but slightly deviated to give the glow around the sun. Air molecules themselves scatter light (hence our blue sky) and thus an aureole is never totally absent.
Diffraction by nearly monosized particles would give a sharply defined aureole surrounded by coloured rings – a corona.
High concentrations of stratospheric dust or sulfate aerosol from volcanic eruption produce a strong and large aureole known as a Bishops Ring, a milky glow fading at the edge to straw and reddish colours.