|Pine Pollen Corona
Jari Luomanen (photography) captured this magnificent example in Finland 28th May '13.
"We had an incredible burst of pine pollen as the trees suddenly seemed to unload all that they had - as if they were synchronized! One could see thick clouds coming off the pines as gusts of wind hit them."
See below for the pollen culprits.
All images ©Jari Luomanen, shown with permission.
|Each oriented pollen grain produces its own oval diffraction pattern.|
|Many rings, oval rings, bright spots. All a direct consequence of the corona's source - pollen grains.
Many rings? With luck - as here - the grains come from a particular type of tree. They are all identical. There is no size or shape variety to produce different sized diffraction patterns that would then add together to smear away the outer rings.
Oval rings, bright spots? Evolution has led to pollen grains that are efficiently dispersed by wind. Each grain has two air sacs that help keep it aloft to drift far and wide. The grains become aligned, oriented, drifting with their air sacs upwards. The oriented grains give, as an accidental by-product of their evolution, oriented and oval diffraction patterns.