Yale Environment 360: Grains of pollen may be seeding clouds and affecting the planet's climate in unexpected ways, University of Michigan researchers write in the journal Geophysical Research Letters. Scientists had assumed that pollen particles were too large to remain in the atmosphere long enough to interact with the sun's radiation or trigger cloud formation. The study found, however, that pollen grains are capable of disintegrating into much smaller particles something that allergy researchers have known for quite...