Major Study Concludes That Cloud Seeding Is Effective

An anonymous reader writes "A 45-year Australian trial is the best evidence yet that cloud seeding — the practice of artificially inducing clouds to make rain — really works."

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Re:Summary != Link

[sakdoctor]

Found correct link: http://www.cosmosmagazine.com/news/2514/major-study-proves-cloud-seeding-effective

Proper URL and text

[grogglefroth]

http://www.cosmosmagazine.com/news/2514/major-study-proves-cloud-seeding-effective

SYDNEY: A 45-year Australian trial is the best evidence yet that could seeding - the practice of artificially inducing clouds to make rain - really works.

Since the mid-20th century scientists have attempted to produce rain by dispersing chemical substances into the clouds and stimulating precipitation. However, until now, there has been little concrete scientific evidence that cloud seeding is effective.

"This is the first time that an independent analysis of cloud seeding data over several decades has shown a statistically significant increase in rainfall," said Steven Siems, a meteorologist from Monash University in Melbourne and leader of the study.

Significant finding

The Monash team, in conjunction with renewable energy firm Hydro Tasmania, analysed monthly rainfall patterns over the hydroelectric catchment area between May and October from 1960 until 2005.

As they detailed in the Journal of Applied Meteorology and Climatology the analysis revealed higher levels of rain in the parts of the catchment where the rain making technique was used than in those where it was not.

"A number of independent statistical tests showed a consistent increase of at least five per cent in monthly rainfall over the catchment area," said Siems.

For the could seeding technique, the researchers select clouds using specialist weather radar technology that allows them to see all the tiny processes that take place within them.

Once clouds for seeding are chosen, minute particles of a silver compound are dusted into them by light aircraft to stimulate rain formation.

Super-cooled water

Anthony Morrison, a climatologist at Monash and co-author of the study, explained that these silver particles cause super-cooled water in the clouds to freeze. As these particular clouds are so high in the atmosphere that they are below freezing point, the frozen drops recruit water and get heavier causing them to fall from the clouds as rain.

However, the researchers caution that the result may be due to the unique clouds in this part of Tasmania and would be difficult to reproduce elsewhere.

"Clouds over the Southern Ocean are different to any other clouds", Siems told Cosmos Online. "They are really loaded with super cool liquid water." Just as important, he said, is the remoteness of the location: "the air in the Southern Ocean is exceptionally clean with virtually no pollution."

And the researchers are still at a loss to precisely explain how the technique was successful.

"They're really not comparable to clouds that have been seeded anywhere else in the world," said Morrison. "Further field measurements of cloud microphysics over the region are needed to provide a physical basis for these statistical results."

Despite the caveats, other experts are excited by the results.

"At long last there is scientific backup for the [cloud seeding] hypothesis that has been suggested over the years," commented Roger Stone, director of the Australian Centre for Sustainable Catchments at the University of Southern Queensland in Toowoomba.

However, while the study is a breakthrough, he noted that cloud seeding does not work in all locations and specific techniques have to be developed for each region.

"For example, in Queensland the conditions are highly different. It has to be the right time and exactly the right cloud for it to work," he said. "The key is to get a very good weather radar."

Let it snow

Paul Johnson, a spokesperson from Snowy Hydro, who are conducting similar experiments to artificial induce snowfall in Victoria's Snowy Mountains, said the results were promising. "It's another indicator that supports our preliminary data and backs up what the experts said in the beginning. That we would see an increase in snow."

Because of the unusual nature of

Re:Terraforming the Earth

[R2.0]

"painting all roofs white to increase the albido,"

It's "libido" or "albedo". Although I'm not sure what the color of the roof has to do with what goes on underneath it.