PhysOrg: Airborne particles known as "aerosols" strongly impact the way clouds form and change, but accurately capturing this effect in computer climate models has proved to be notoriously difficult. A new study in the Proceedings on the National Academy of Sciences Early Edition online Feb. 26 suggests why-either the models are failing to capture in sufficient detail the processes at work in clouds, or aerosols are now so pervasive in the atmosphere thanks to modern-day pollution that their specific effects...