Atmospheric aerosols seem to boost the intensity of rainfall over large areas of land and ocean.

Aerosols — tiny particles that include black carbon and sulphates — influence cloud properties, but whether the overall effect produces more or less rain has been uncertain. Ilan Koren at the Weizmann Institute of Science in Rehovot, Israel, and his colleagues looked at satellite observations of rainfall, aerosols and clouds between June and August 2007, and compared them with meteorological data. They found that increases in aerosol abundance correlated with a higher rate of rainfall in the tropics, subtropics and mid-latitudes.

The authors say that the similar trends seen across different locations and environmental conditions suggest a link between increased aerosol levels and more intense rainfall.

Nature Geosci. http://dx.doi.org/10.1038/ngeo1364 (2012)