Lunar & Solar Pollen Coronae, Russia
Captures by Sergei Antipov some some 50km from Murom, a historical city in Vladimir Oblast.
All images ©Sergei Antipov, shown with permission
Near sunset on May 5. Smooth rings.
May 26. More elongated lumpy rings. This later corona is probably from pine.
Pine pollen grains have air sacs to help wind dispersal. The sacs also align the grains to give a sharp diffraction pattern with spots of higher intensity.
The earlier birch pollen is less asymmetric and its coronal rings are smoother.
One of Sergei's images from 2014.
Here the bright spots of a pine corona are well defined.
This May 5 lunar shot shows well the corona's elongation.
The moon’s gentle rays create a delicate elongated corona with two and perhaps even three rings in places. Sergei took this and the accompanying near sunset solar corona on May 5, ’15. More coronae from May 26th are below. Each Spring the region has regular coronae. Birch releases its pollen early in May and pine blooms towards the month’s end.
Pollen coronae, like the more familiar ones from cloud water droplets, arise when the grains individually scatter light waves. The outgoing waves are in-phase in some directions and out-of-phase in others. A sky projected diffraction pattern results.
Pollen coronae are characteristically non circular and of several well defined rings. The shape comes from the non-spherical grains aligned by aerodynamic drag. The many rings from their constancy of size.