|Peder Mønsted, A Winter's Day|
The effect comes from light scattered by water vapor and dust in the air between you and the sun. The light is further scattered by your eyelashes when you squint, and then by the aqueous humor and vitreous fluid of the eye. The effect is best observed when you glimpse a setting sun through trees or when you see a streetlight at night.
Try squinting hard at a streetlight and tilting your head to see how the rays tilt with you. Also, try walking through the forest where the sun is mostly blocked by branches and glance up toward the sun as you walk to see how the corona comes and goes.
|Giuseppe Pellizza (Italian, 1868-1907) Volpedo, The Sun, 1904|
Lens flare is easy for digital artists to add, and a little harder for physical painters, depending on the technique. As a photographic effect, it has origins in camera optics. Its artistic use—and overuse—in film, television, and photography is well explained in this Vox video (link to YouTube). Thanks, Dan.
Related GurneyJourney posts:
How to Get a Feeling of Misty Light
More of this kind of stuff in my book Color and Light: A Guide for the Realist Painter