Cloud seeding can be considered as a part of weather modification (or engineering), which relates to regulation of precipitation (both quantitatively and alteration of type) in a certain area. The process can be achieved by distributing artificial substances like silver iodide and dry ice (frozen carbon dioxide) into the air that serve as cloud condensation or ice nuclei. This effectually changes the micro-physical formations and bearings within the cloud. Now the usual aim in most of the cases is to accentuate upon the magnitude of rainfall, but in other scenarios cloud seeding is also envisaged as a preventive measure for hail and fog suppression (especially in case of airports).
The advantages are quite evident, specifically when we take into account the systematic drought experienced by wide stretches of arid regions all throughout the world, with examples like the Saharan region or the Russian Steppes. This is where dynamic cloud seeding comes into the picture, by enhancing the quantitative amount of rainfall over an area. The largest cloud seeding system in the world is that of the People’s Republic of China, who’s administration believes that it increases the amount of rain over several increasingly arid regions, including its capital city, Beijing, by firing silver iodide rockets into the sky where rain is desired.
Moreover, cloud seeding also has the potentiality of controlling the weather by prevention of flooding (excess rainfall) or even creating favorable conditions for various modes of transportation like aircrafts and ships. Many areas such as 11 western states in the US, Alberta province in Canada and Tasmania province in Australia are already undergoing weather-modification programs related to this.
Can this be better?
Yes, with the further progression of this technology, the end results are expected to be even more efficacious. The broader scope for development of the whole geo-engineering system is always there.
One of the most common chemicals used for cloud seeding include silver iodide. Now, according to studies – “with an NFPA 704 rating of Blue 2, silver iodide can cause temporary incapacitation or possible residual injury to humans and mammals with intense or continued but not chronic exposure.”
Though, it should be duly noted that the toxicity of silver and silver compounds (from silver iodide) was shown to be of low order (negligible environmental and health impacts) in some further studies.
Can this be avoided?
Resoundingly yes, by lowering the intensity of silver iodide in the process. Moreover, there are other processes that utilize the expansion of liquid propane into a gas, though it is achieved at a higher temperature for generation of ice crystals. Even some processes call for the usage of hygroscopic materials, such as salt for further lowering of harmful effects.
Sometimes the procedure can get out of ‘control’, for various reasons starting from the nascent stage of technological progress to clear ineptitude on part of the controllers (people) in some cases. One such example is the Operation Cumulus project (one of the very first cloud seeding projects undertaken officially), carried out by the British Royal Air Force on orders from the UK government, during the period of August 4-15, 1953. There are widespread speculations that a flood in Devon killing 34 people was a direct effect of this secretive project.
A more recent, smaller-scale mishap occurred in June 2008, when the Russian Air Force on a cloud seeding procedure over Moscow, accidentally dropped a mixture of silver iodide, liquid nitrogen and cement powder. The cement bag crashed through a roof of a suburban house, after failing to turn to powder.
Why are we so critical?
Impact on environment and health:
Just like geo-engineering, weather modification in form of cloud seeding as an instrument of modernistic technology is very real, as are the somewhat climatic (or to some degree even materialistic) threats posed by its ineffectual handling.
There is no doubt that cloud seeding is indeed an ingenious and relatively environment friendly method (at least as compared to other technologies found in the geo-engineering arsenal) to get nature into ‘our side’. But once we move away from the theoretical perspective, there have been issues – like concern of environmentalists about the uptake of elemental silver in highly sensitive ecological conditions, or even the uncontrollable nature of the process itself (in few cases) due to nascent advancement of the technology. So full fledged progression is certainly necessary, and who knows clouding seeding can even circumvent its current scope and make our desert regions lush and fertile again!