A not-so-rainy day

摘要

It is an old chestnut that every cloud has a silver lining. But a study published in this week's Science, by Daniel Rosenfeld of the Hebrew University of Jerusalem, suggests that the proverb works at several levels. Dr Rosenfeld studies the effects of a metaphorical cloud—industrial pollution—on real clouds of the fluffy, white sort found in the sky. His results show that pollution makes clouds shine, if not exactly silver then at least more brightly. They also suggest that people who live downwind of sources of pollution should suffer less rainfall than their not-so-favoured neighbours.