|Corona Rings ~
An intense multi-ringed corona around the sun by David Smith at Columbus, Indiana. ".. the best I could do with a basic Iphone 3. It really does not do the corona justice. I was amazed at the number of rings, it was truly spectacular. Oh, and those little specs just up and to the right of the parking lot light are a flock of migrating Sandhill Cranes."
©David Smith, shown with permission
|Red and green image channels were subtracted to enhance colour features and especially the rings which now appear dark. There are definitely four present and possibly more.|
|A Mie computation of corona intensity. The green line is for monochromatic green light (500nm). The first green ring is already down to 1/50th of the central intensity. Then the rings fall off in brightness more slowly and we might therefore expect to see many rings more often.
White light is enemy number one as the white intensity profile shows – intensity wise we now have difficulty picking out the ring positions. Coronae of different colours are different sized and beyond the first ring the colour overlap wipes out intensity variations leaving only colour differences to identify the rings. Enemy number two is droplet size variations. Coronae, produced by single droplet diffraction, are larger the smaller the droplet. A cloud with many sized droplets will produce coronae with fewer rings.