Pollen Corona Over Trier, Germany
October 09, 2008
Referred by: Eva Seidenfaden
Summary Author: Eva Seidenfaden, Jim Foster
This spectacular pollen corona was observed above Trier, Germany on May 12, 2008. It occurred after a long period of warm, dry weather -- when there was considerable pollen in the lower troposphere. It's thought that the pollen grains are from pine and fir trees. As with the case for water droplets or very small ice particles, airborne pollen grains can also produce diffraction coronae. A clue to the fact that this corona was formed from pollen is its peculiar oblong shape -- irregularly shaped pollen will produce non-circular corona. Pollen corona are more apt to be seen if pollen counts exceed 2,000-4,000 particles per cubic meter.