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How Do You Know Which Clouds to Target?

The monsoons this year have been a bit of a disappointment. So much so that some state governments are pinning their hopes on cloud-seeding. To understand the concept, we spoke to Arvind Sharma, CEO, Agni Aviation, the only company in India that offers you rain on demand

Published: Sep 25, 2009 12:01:00 AM IST
Updated: Sep 25, 2009 05:00:43 PM IST

What is cloud-seeding? Is it artificial rain?
No, it’s natural rain that is precipitated by introducing certain elements into the cloud. Every raindrop is built around a nucleus called the cloud condensation nuclei (CCN). This particle forms the core around which there is a cloud deposit. We need these nuclei to form the raindrop. In nature, salt from the oceans, volcanic ash, even car exhaust yields the particles that function as CCNs. When we seed clouds, all we’re doing is introducing these nuclei by artificial means.

Indians have traditionally resorted to yagnas and havans for rain. Does this help?

Surprisingly, there could be a grain of science in this. Sitting on top of a mountain and starting a fire with various herbs and other materials thrown in, could, in theory, send particles into the clouds that become CCNs. The co-relation between smoke and rain was first observed during the US civil war. They found that it usually rained at the end of the day after a lot of cannon-firing. This, we now know, is because the dust and smoke created CCNs in the clouds and caused precipitation. Later, people began sending salt into the clouds by using kites and artillery shells.

How do you know which clouds to target?
Clouds are selected based on their water content and the thermal activity around them. Aircraft can then target the right kind of clouds. What helps tremendously here is weather radar. Advanced software has enabled us to study the cross sections of clouds to determine whether they are ready for seeding.
There are two types of clouds: Warm clouds, which are lower down and are above freezing point and cold clouds, which are below freezing point. Warm clouds are seeded using sodium chloride (common salt) and silver iodide is used for cold clouds.

With cloud-seeding via airplane, who leads the process, weather scientists or the pilot?
It is a combination of both. We absolutely have to look at the meteorological charts for the day to analyse the cloud cover in the region. There cannot be any rain if there are no clouds of the right type. The plane takes off only if the conditions are right, it reaches the base of the cloud and looks for an updraft (warm air going upwards). Then it flies upwards doing tight turns and releases the salt. If all goes well it starts raining within 25 to 30 minutes.

What are observable negative aspects of seeding clouds?
This is climate engineering. The reality is that we have already used up surface and ground water resources. Aerial water resources are the only ones yet to be tapped. A bad monsoon can severely impact an agricultural economy like ours. But there are no answers yet on the ill-effects. Scientists are still trying to study the impact of this process. In the US, there is a licensing policy and zones are demarcated between various states.

(As told to Cuckoo Paul)

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(This story appears in the 09 October, 2009 issue of Forbes India. To visit our Archives, click here.)

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  • T.V.Rama rao

    Business Magnets must be Honest.<br /> Prof T. Shivaji Rao,an international expert on cloud seeding is questioning why business lobby in india are dullards by their apathy towards cloud seeding because they are killing the goose that lays the Golden Eggs in the form of making available more rain than what the clouds offer to man in their usual course due to lack of sufficient quantities of nnuclei that impregnate the clouds to become more efficient in delivering more rain which is BLUE GOLD.<br /> It is blue gold because it promotes agriculture,hydro-power production,additional water for drinking and industrial use in cities like Mumbai,chennai,bangalore,hyderabad,kolkatta,New Delhi which are not getting sufficient municipal waters from the conventional sources like rivers and ground waters.In order to augment these sources we need to conduct cloud seeding operations as followed in China,Australia,Texas and Japan..<br /> Even if Indian officials,meteorologists,scientists and politicians are against cloud seeding because it produces more rain to benefit the farmers and the general public,Industrialists must take the lead and visit China and Texas and prepare reports on how cloud seeding can help to save agriculture and industrial development.So Tatas,Ambanis,Birlas and other industrialists and intelligent BJP chief ministers like Modi should take the lead in this direction and show that Indian leaders are genuinely interested in serving the people of India.For more details,any honest industrialist in India can contact the Experts like like prof.T.Shivaji Rao and Dr.J.V.M.Naidu,formerDy. Director General,IMD how to mitigate the water scarcity expected in 2010 to save Indian population from drought conditions<br /> T.V.Rama Rao.M.Com.,<br />

    on Jan 3, 2010
  • prof.T.Shivaji Rao

    Why Business Magnets are Dullards in using cloud seeding for Business?<br /> Capt.Arvind sharma rightly pointed out how cloud seeding is done to augment rainfall even during droughts when some clouds are likely to be present in the sky. When normal clouds give only 10% of their water content as rainfall, the injection of chemicals into them increase their water delivery by 25 to 30% at a cost benefit ratio of 1:20 to 1:60.In 40 to 50 countries cloud seeding is done for over 40 to 50 years and the Business is highly beneficial. But Indian business men are too dull to recognise that water is Blue Gold and cloud water is the third water resource in the clouds in the atmosphere in amounts ten times more than the water contained in all the rivers on Earth. China is employing 37000 technicians to produce 65 billion cubic meters of additional rain water per year at a cost benefit ratio of 1:27. Hydro-power is generated at a cost benefit ratio of 1:20 in Tasmania and Honduras.<br /> When China is investing Rs.400 crores per year on cloud seeding to augment water supplies for saving the agriculture and industrial production, why is it that Indian businessmen choose to remain dullards in tapping this tertiary water source atleast when the primary surface water and secondary ground water resources have been exhausted due to the growth of population, industrialisation and Urbanisation? For more details,see web sites:<br /> http://www.usatoday.com/news/world/2006-06-29-china-rain_x.htm <br /> http://www.gitam.edu/cos/env/English-Book.pdf <br /> http://jcsepa.mri-jma.go.jp/outreach/20070131/Presentations/P3_Yao.pdf <br /> http://shivajirao.cloudseeding.googlepages.com/scienceofcloudseeding <br /> http://video.vividas.com/media/4375_snowyhydro/web/ <br /> http://bigcountryhomepage.com/content/fulltext/?cid=176451 <br /> prof.T.Shivaji Rao,<br /> Director,Gitam University,and<br /> Expert,cloud seeding project of Government of Andhra Pradesh

    on Sep 27, 2009
  • Satya Meva Jayatey from UK

    I challenge the moderator to let the truth be out in public , don't keep it supressed. Excess of everything id bad , this is commonsense. If one keep on consuming sweets in excess he will surely die. We are living inthe world of scientific tyranny and after 80-90years of wrong doing to the masses in the name of science and "FOR YOU" goverment merely say sorry. The Silver Iodide has lots of hazardous effects on the human body , all you see is take a sample of water collected from the cloud seeding rain and test it and declare results to be safe and within the permissible limits. But consuming that permissible limits on daily basis and don't forget the silver iodide or other chemicals used in weather modification programme like alimunium and barium , are coming down to our enviornment and we are inhaling these anao particles and they these so called "with in permissible limits" are getting acumulating in our bodies day by day remember excess of everything is bad. So in real sense this cloud seeding programe is nothing but a SOFT KILL WEAPON against humanity. STOP ALL OF THIS NONSENSE.

    on Jan 16, 2010
  • frozen

    I would like to know things and facts that explains further reason why is salt used an agent in cloud seeding. Some topics are not yet explained, especially about it's components that makes it as an agent. How does it affect the process that naturally happens in the clouds? How does it help? and if it is really effective. Maybe if you will explain further about facts, rather than explaining about superstitious beliefs, readers will surely be happy and satisfied with your article.

    on Feb 13, 2010