The phenomenon was identified by meteorologist Daniel Rosenfeld, of the Institute of Earth Sciences, at the Hebrew University, in Jerusalem. His research into how air pollution stops rain forming was first published in the Science journal last year. Professor Rosenfeld presented the images and research to a meeting of federal agencies in Canberra yesterday. He will also speak at a climate change seminar at Monash University on Friday. Professor Rosenfeld said more research was needed, but pollution from Melbourne and the Latrobe Valley could be costing up to five million megalitres in lost rain.
Air pollution affects rainfall because it contains large amounts of microscopic dust particles.
The particles prevent water vapor in clouds condensing to form drops large enough to fall as rain. His color-coded satellite images show clouds across Victoria with similar structure and water content, except that yellow clouds in the pollution stream are not producing rain and the red clouds to either side are. Dr Rosenfeld said particles stay in the air for about a week, by which time the clouds have evaporated. The water vapor is then blown away from Australia to fall as rain over the sea. He said the images correlate with weather records showing that rain and snow over the high country has declined by 6 per cent over the last century, compared with a general 15 to 18 per cent increase across south-eastern Australia.