|Pollen Corona, Degerby, Finland on
11th June '94 by Marko Riikonen (site) . Image ©Marko
Riikonen, shown with permission.
It little matters for corona formation whether small particles are
transparent or opaque. What does matter is their size and their shape.
year trees of the Northern forests release copious clouds of pollen. The
pollen grains from a given tree variety usually have very similar sizes
- ideal for corona formation.
Unlike water droplets, pollens are non spherical. Many have air
sacs to assist wind dispersal and they are consequently become specially
oriented as they drift in the air. The result is elongated
coronae, sometimes with bright patches on their rings.
Pollens are comparatively large and so their coronae are small. Look close
to a well shielded sun (take care of your eyes!) or, preferably, search
for them in the reflection of the sky in a pool or dark glass.
Another pollen corona.