Can We Control The Weather?

A science fiction writer might imagine a future in which a government official -- the Minister of Weather Modification, perhaps -- dials up the day's weather for his country's citizens. A drought in the West? No problem, we'll just order a few gentle showers. A hurricane threatening the East Coast? Just stay calm, folks, we'll launch a small nuke to blast the storm apart. 

They say truth is stranger than fiction, and such is the case with humans attempting to control the weather. Let's start with a brief history. Numerous Native American tribes, especially those living in semiarid desert country, such as the Pueblo, Hopi and Zuni, engaged in elaborate dances to coax moisture from the rain-stingy skies. In the late 1800s and early 1900s, rainmakers roamed across the western United States, promising to end droughts for a fee.

These itinerant salesmen used a combination of pseudo-science and grand showmanship to convince communities that their technique, often a device or structure used to deliver chemicals or gases into the air, would bring rain in short order. Even the U.S. government got in on the act. In 1891, Congress appropriated $19,000 to conduct rainmaking tests in Texas under the guidance of Robert Dryenforth. Dryenforth's results were inconclusive, and as the century turned, politicians and citizens began to regard rainmakers with increasing skepticism.

It would take another four decades before the scientists involved with weather control began to overshadow the charlatans. The real turning point came in 1946, when Irving Langmuir and Vincent Schaefer, chemists working at General Electric Research Laboratory in Schenectady, N.Y., discovered that they could introduce ice crystals into a supercooled cloud and create snow. They called the process glaciogenic cloud seeding and soon enlisted the help of physical chemist (and brother to novelist Kurt Vonnegut) Bernard Vonnegut.

Vonnegut searched for another crystalline substance that would have a similar effect, and he found it in silver iodide. Over time, the team worked out the basic science of cloud seeding, which goes like this: Often, the drops of moisture in clouds can't freeze without some extra help. If these drops encounter crystals of silver iodide, they glom onto the crystals and freeze. Once the ice grows big enough, it falls from the cloud, either as snow or, if it passes through warmer air, as rain.  

Planting the Seeds of Weather Modification

Finally, scientists had found a way to control the weather -- at least in the lab. For the next 30 years, researchers and entrepreneurs across the world began applying the principles developed by Langmuir, Schaefer and Vonnegut to real-world cloud seeding. They flew airplanes into the clouds, releasing their own clouds of silver iodide as they went, or fired artillery shells filled with silver iodide into clouds. In some cases, these weather modifiers were trying to produce rain in drought-afflicted areas, mitigate hail damage by preventing hailstones from growing so large, or disperse fog banks around airports. Many proprietors of this new technology made audacious claims about their cloud seeding services. Unfortunately, hard science could never substantiate the claims. If anything, rigorous experimentation seemed to suggest that cloud seeding barely worked or, worse, didn't work at all.

Still, enough tantalizing evidence has accumulated over the years to keep interest in weather modification alive. For example, research conducted in South Africa and Mexico has shown that seeding warm rain clouds with salt particles -- what is known as hygroscopic seeding -- is more effective than seeding cold rain clouds with silver iodide. And Chinese scientists believe they have mastered cloud seeding to such a degree that they can guarantee a certain day will be rainy or sunny, like say the opening ceremony of the 2008 Summer Olympics in Beijing, as this related article describes.

 

It's one thing to control precipitation from a few clouds over a localized area. But is it possible to prevent hurricanes from forming? Some scientists think so. Computer modeling of recent major hurricanes, such as 1992's Andrew, reveals how even one or two small changes could have turned a major catastrophe into a minor storm. This is the heart of chaos theory, a set of scientific principles describing highly complex systems, such as weather systems, where small changes in initial conditions radically change the final results.

Now meteorologists wonder whether they could put chaos to good use to prevent hurricanes from forming in the first place. If they could change one or two variables just as an Atlantic storm is beginning to coil itself into a monster, maybe they could diminish its strength or divert its path. 

Changing sea temperatures seems the most likely scenario, and a few scientists have proposed coating the ocean surface with a thin layer of biodegradable oil. This could, in theory, reduce evaporation, the process that drives hurricane formation. Similar ideas could work on tornadoes, as well. One physicist has proposed disrupting funnel-cloud formation by zapping the atmosphere with beams of microwaves shot from solar-powered satellites.

But right now, this sounds like more science fiction, where controlling the weather remains as easy as flipping a switch on the Weather Modification Machine and dialing up just the right amount of rain, snow or sun. 

by "environment clean generations"

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Posted in: Can We Control The Weather?,cloud,earth,precipitation,rain,storm,sun,weather

Weather Affected By Microbes

       Bacteria have been discovered in hailstones, with the highest concentrations of germs in the cores. Ice-nucleating bacteria in clouds could trigger snow and ice storms. Bacteria in cloud can also boost the production of a greenhouse gas, contributing to global warming. 

               Bacteria often leave their hosts feeling under the weather. And even when the hosts are high-altitude parcels of air, microbes can be a source of inclement conditions, a Montana research team finds. Cloudborne bacteria might even pose climate threats by boosting the production of a greenhouse gas, another team proposes. Both groups reported their findings May 24 at the American Society for Microbiology meeting in New Orleans.

              These data add to a growing body of evidence that biological organisms are affecting clouds, notes Anthony Prenni of Colorado State University in Fort Collins, an atmospheric scientist who did not participate in the new studies. Right now, he cautions, “We still don’t know on a global scale how important these processes are.” But research into microbial impacts on weather and climate is really heating up, he adds, so “within a few years, I think we’re going to have a much better handle on it.”

             Alexander Michaud’s new research was triggered by a June storm that pummeled Montana State University’s campus in Bozeman last year with golf ball–sized and larger hailstones. The microbial ecologist normally studies subglacial aquatic environments in Antarctica. But after saving 27 of the hailstones, he says, “I suddenly realized, no one had really ever thought about studying hailstones — in a layered sense — for biology.”

             So his team dissected the icy balls, along with hundreds of smaller ones collected during a July hail storm south of campus. Michaud now reports finding germs throughout, with the highest concentrations by far — some 1,000 cells per milliliter of meltwater — in the hailstones’ cores.

             Since at least the 1980s, scientists have argued that some share of clouds, and their precipitation, likely traces to microbes. Their reasoning: Strong winds can loft germs many kilometers into the sky. And since the 1970s, agricultural scientists have recognized that certain compounds made by microbes serve as efficient water magnets around which ice crystals can form at relatively high temperatures (occasionally leading to frost devastation of crops).

                

         In 2008, Brent Christner of Louisiana State University in Baton Rouge and his colleagues reported isolating ice-nucleating bacteria from rain and snow. A year later, Prenni’s group found microbes associated with at least a third of the cloud ice crystals they sampled at an altitude of 8 kilometers.

         “But finding ice-nucleating bacteria in snow or hail is very different from saying they were responsible for the ice,” says Noah Fierer of the University of Colorado at Boulder. “I say that,” he admits, “even though as a microbiologist, I’d love to believe that bacteria control weather.”

                  Pure water molecules won’t freeze in air at temperatures above about –40 degrees Celsius, Christner notes. Add tiny motes of mineral dust or clay, and water droplets may coalesce around them — or nucleate — at perhaps –15 degrees. But certain bacteria can catalyze ice nucleation at even –2 degrees, he reported at the meeting in New Orleans.

                 Through chemical techniques, Michaud’s group determined that the ice nucleation in their hail occurred around –11.5 degrees for the June hailstones and at roughly –8.5 degrees for the July stones.

                 Michaud’s data on the role of microbes in precipitation “is pretty strong evidence,” Prenni says.

Also at the meeting, Pierre Amato of Clermont University in Clermont-Ferrand, France, reported biological activity in materials sampled from a cloud at an altitude of 1,500 meters. The air hosted many organic pollutants, including formaldehyde, acetate and oxalate. Sunlight can break these down to carbon dioxide, a greenhouse gas, something Amato’s group confirmed in the lab. But sunlight didn’t fully degrade some organics unless microbes were also present.

 

          Moreover, certain cloudborne bacteria — the French team identified at least 17 types — degraded organic pollutants to carbon dioxide at least as efficiently as the sun did. Amato’s team reported these findings online February 9 in Atmospheric Chemistry and Physics Discussions.

           This microbial transformation of pollutants to carbon dioxide occurs even in darkness. Amato has calculated the total nighttime microbial production of carbon dioxide in clouds and pegs it “on the order of 1 million tons per year.” Though not a huge sum (equal to the carbon dioxide from perhaps 180,000 cars per year), he cautions that this amount could increase based on airborne pollutant levels, temperatures and microbial populations.

by "environment clean generations"

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Posted in: microbes,water,weather