06-18-2008, 10:32 PM
Dan Glaister in Los Angeles The Guardian,
Wednesday June 18 2008
Eight hundred thousand dollars should buy a lot of water. But in Los Angeles county, where a recently declared drought is starting to bite, politicians plan to spend that much firing silver iodide particles into the sky in the hope of boosting rainfall by as much as 15%.
"There are no assurances or guarantees that it will produce anything," Richard Hansen, general manager of Three Valleys municipal water district told the Associated Press. "But it doesn't hurt to try."
Los Angeles engaged in cloud-seeding from the 1950s to the 1990s, when the practice was suspended because of concerns that it could trigger landslides.
But other areas, including nearby Santa Barbara, have continued to use the method, typically employing aircraft or ground-based generators to spray silver iodide above mountains.
Los Angeles county plans to place generators along the foothills of the San Gabriel mountains, north of the city. The generators will use propane burners to spray the particles into the air, where the silver iodide will interact with clouds to create additional ice crystals. The exercise will take place during the winter rains, to minimise risk of fire and because there need to be natural clouds.
A study by the National Academy of Sciences released in 2003 found no evidence that cloud-seeding worked, although experts acknowledge it is difficult to gauge whether a cloud is producing more rain than it might normally do.
"It's something that I wish there were more good hard research on," Maury Roos, California's chief hydrologist told the Los Angeles Times. "I think there's something to it. The question is, how much, versus how much is it going to cost?"
Should the practice catch on, it will mark a return to one of southern California's obsessions with modifying nature and the exploits of Hatfield the Rainmaker.
Practising his craft in the early years of the 20th century, Charles Mallory Hatfield would place "evaporating tanks" filled with chemicals in drought-affected areas. His most notable claim was to coax 16 inches of rain (about 41cm) in two days from the skies over San Diego in 1916. The city, however, refused to pay Hatfield, declaring: "We told you merely to fill the reservoir - not to flood the community."
http://www.guardian.co.uk/world/2008/jun/18/usa.water
Wednesday June 18 2008
Eight hundred thousand dollars should buy a lot of water. But in Los Angeles county, where a recently declared drought is starting to bite, politicians plan to spend that much firing silver iodide particles into the sky in the hope of boosting rainfall by as much as 15%.
"There are no assurances or guarantees that it will produce anything," Richard Hansen, general manager of Three Valleys municipal water district told the Associated Press. "But it doesn't hurt to try."
Los Angeles engaged in cloud-seeding from the 1950s to the 1990s, when the practice was suspended because of concerns that it could trigger landslides.
But other areas, including nearby Santa Barbara, have continued to use the method, typically employing aircraft or ground-based generators to spray silver iodide above mountains.
Los Angeles county plans to place generators along the foothills of the San Gabriel mountains, north of the city. The generators will use propane burners to spray the particles into the air, where the silver iodide will interact with clouds to create additional ice crystals. The exercise will take place during the winter rains, to minimise risk of fire and because there need to be natural clouds.
A study by the National Academy of Sciences released in 2003 found no evidence that cloud-seeding worked, although experts acknowledge it is difficult to gauge whether a cloud is producing more rain than it might normally do.
"It's something that I wish there were more good hard research on," Maury Roos, California's chief hydrologist told the Los Angeles Times. "I think there's something to it. The question is, how much, versus how much is it going to cost?"
Should the practice catch on, it will mark a return to one of southern California's obsessions with modifying nature and the exploits of Hatfield the Rainmaker.
Practising his craft in the early years of the 20th century, Charles Mallory Hatfield would place "evaporating tanks" filled with chemicals in drought-affected areas. His most notable claim was to coax 16 inches of rain (about 41cm) in two days from the skies over San Diego in 1916. The city, however, refused to pay Hatfield, declaring: "We told you merely to fill the reservoir - not to flood the community."
http://www.guardian.co.uk/world/2008/jun/18/usa.water