Cleansing Rain? Not So Fast

Scientists have found that rain triggers the release of a mist of particles from wet soils into the air, a finding with consequences for how scientists model our planet's climate and future. (Credit PNNL) This article was adapted from a news release by Pacific Northwest National Laboratory. Rain's reputation for cleansing the air may come with a caveat after new study findings show that they play a role in generating airborne organic particles. The surprising results, published today , show that when droplets hit the dirt, particularly in grasslands and tilled fields, they launch a mist of microscopic particles into the air. The mechanism begins as organic matter in the soil dissolves in the puddles when it rains. Subsequent raindrops create air bubbles in the puddles that mix with the dissolved matter. The bubbles float upward and quickly burst, releasing into the air a mist of the soil organic compounds.