"Pine is strongly flowering now in middle Finland, and the coronas have been quite impressive over the past few days," says Vauhkonen. "Pollen is everywhere--not only in noses and eyes, but also around the setting sun."
Atmospheric optics expert Les Cowley explains the phenonenon: "Coronas are produced when light waves scatter from the outsides of small particles. Tiny droplets of water in clouds make most coronas, but opaque equal-sized pollen grains do even better. They make small but very colorful multi-ringed coronas."
"Unlike water droplets, pollens are non-spherical--and this adds to their magic," he continues. "Many have air sacs to help carry them in the wind. These align the grains to give beautiful elliptical coronas with bright spots." This is why Vauhkonen's pollen corona looks the way it does.