Weatherwatch: tiny particles in the air can trigger massive storms

US scientists taking measurements above the Amazon rainforest have recorded the effects of smoke and aerosols on the weather

Mankind has made the world warmer, but we've also made it stormier. In a study conducted over the Amazon rainforest, scientists have shown that tiny particles - smaller than one-thousandth of the width of a human hair - cause storms to intensify, and potentially have knock-on effects for weather around the world.

Jiwen Fan, from the US Department of Energy's Pacific Northwest National Laboratory studied storm formation near the Brazilian city of Manaus. Its 2 million people make Manaus the largest city in the Amazon, and the busy streets and smokey chimneys produce a near permanent pollution plume.