We have all realised the importance of rainfall. The present finance minister, many scholars and economy controllers have many a times acknowledged the fact that rains after all are the real finance ministers. As we wait for the forthcoming new drops of this year, I thought of sharing a small example of artificial rain creation technique. I am sure many of you would be aware of it; the interested souls may conact google for more enlightenment. Hope you like it!
Cloud seeding, a form of weather modification, is the attempt to change the amount or type of precipitation that falls from clouds, by dispersing substances into the air that serve as cloud condensation or ice nuclei, which alter the microphysical processes within the cloud. The usual intent is to increase precipitation (rain or snow), but hail and fog suppression are also widely practiced in airports.
There are three cloud seeding methods: static, dynamic and hygroscopic.
• Static cloud seeding involves spreading a chemical like silver iodide into clouds. The silver iodide provides a crystal around which moisture can condense. The moisture is already present in the clouds, but silver iodide essentially makes rain clouds more effective at dispensing their water.
• Dynamic cloud seeding aims to boost vertical air currents, which encourages more water to pass through the clouds, translating into more rain. Up to 100 times more ice crystals are used in dynamic cloud seeding than in the static method. The process is considered more complex than static clouding seeding because it depends on a sequence of events working properly. Dr. William R. Cotton, a professor of atmospheric science at Colorado State University, and other researchers break down dynamic cloud seeding into 11 separate stages. An unexpected outcome in one stage could ruin the entire process, making the technique less dependable than static cloud seeding.
• Hygroscopic cloud seeding disperses salts through flares or explosives in the lower portions of clouds. The salts grow in size as water joins with them. In his report on cloud seeding, Cotton says that hygroscopic cloud seeding holds much promise, but requires further research.
¬Criticism
Cloud seeding is quite expensive, though potentially cheaper than other projects, like diverting rivers, building new canals or improving irrigation systems (aimed towards better agricultural productivity). Then again, the allure of cloud seeding may redirect attention and funding from other projects that could be more promising. Then there are questions about altering weather. Are some areas taking moisture out of the air that would have fallen as rain in another region? Despite reassurances from cloud-seeding companies, concerns also remain about expo¬sure to silver iodide toxicity and soil contamination.
Famous works / examples
¬China has a reputation for launching ambitious projects, from the Great Wall in ancient times¬ to the highest railroad in the world, connecting Qinghai to Tibet. But is the investment in cloud seeding worth it, and can the government really make it rain whenever it sees the need?
The Beijing Weather Modification Office spent a lot of time researching how to prevent rain in the city during the Aug. 8 opening ceremony of the 2008 Summer Olympics. The government even guaranteed clear skies for the event -- a promise it managed to deliver on. The feat only took the launch of 1,104 rain dispersal rockets from 21 sites in the city to pull off.
As I always say brickbats and bouquets welcome!
-Sukhi
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