Cloud seeding seems to be the cheapest and most viable option that a government can have when it comes to augmenting water resources
EVERY dark cloud, they say, has a silver lining, but these days with prospects of a decent monsoon fading fast, every dark cloud passing by brings on a muted cheer. For when nothing else remains, there is still cloud seeding, and if the BMC goes ahead with its planned Weather Modification experiment in the right manner and the government approves of it, there is still hope.
According to country’s leading Weather Modification scientist, Prof T. Shivaji Rao, Director, Centre for Environmental Studies, Gitam University at Visakhapatnam, “It is the cheapest and most viable option that a government can have when it comes to augmenting existing water resources”.
But Prof. Rao blames the unholy nexus between the water tanker lobby, politicians patronizing the tanker lobby, Union Agriculture Minister, Union Science and Technology Minister and sections of the scientific community itself, who drub the cloud seeding technology as being too expensive so that their vested interests are served. “Between 2004 and 2009, along with some of our local scientists we carried out cloud seeding in Andhra Pradesh with encouraging results”, claims Prof Rao.
“Drought condition is a cloak behind which they hide to sanction relief funds which ultimately end up a kickbacks to the MPs and MLAs. The tanker lobby is very active in ensuring that these experiments are never a success. Constitutionally speaking, under article 51 (a), (g) the Union Agriculture Minister, Union Science and Technology Minister should be promoting cloud seeding in our country in places facing drought. But they never have whole-heartedly supported it”.
At such times it is only the farmer and the scientist who are left to stare at the skies for any tell-tale signs of cloud bank building up on the horizon that could signal rain. But not all clouds have a silver lining when it comes to the question of cloud seeding. Out of the 10 prominent cloud varieties, it is only the Cumulonimbus cloud variety (better known as the thick vertical clouds) that can have the capacity to produce rain. According to Prof Rao the clouds have to be fairly closer to the ground level so that cloud seeding can produce the desired results.
But for that, he argues, the meteorological conditions, the weather, the clouds, wind direction and the geographical terrain play an important role in determining the success of the experiment. “The technology is 100 percent proven. But the outcome will vary from place to place or say a country or a region and on the expertise of the experts themselves”, says Prof Rao.
Weather Modification, better known as cloud seeding, involves simple technology of injecting clouds with chemicals that encourage water vapor to form ice crystals heavy enough to fall, melting on their way to produce rain. The most common chemicals used in cloud seeding are Silver Iodide, Dry Ice or solid Carbon Dioxide, Liquid Propane and even Sodium Chloride (Common Salt). Cloud seeding can be done at ground level using ground level generators, by firing canisters filled with chemicals from the ground into the clouds and by spraying them from a aircraft. In case of aircraft, Silver Iodide flares are ignited and dispersed as the aircraft flies through the cloud bank.
According to Prof Rao, more than 50 countries around the world like the US, Canada, Honduras, South Africa, Israel, Russia, Australia, Singapore, China and many more have been doing it consistently over the years now to regenerate their ground and surface water resources. China did it just before the 2008 Beijing Olympics to clear the skies of clouds before the opening ceremony. It is another way to tap the atmospheric clouds to produce 10 percent more of water than one can get by a normal monsoon.
Much depends upon how thick the Cumulonimbus cloud bank is. This cloud variety can extend anywhere between 1 or 2 Kms from the ground level and its tip to anywhere between 13 to 15 Kms into the stratosphere. These clouds contain super cool water, ice crystals and water vapor. The temperature in these clouds is around minus 40 degrees Celsius. Once sprayed with chemicals like Silver Iodide or Sodium Chloride, the chemical crystals interact with the liquid crystals which are not more than 20 microns (roughly one-third in thickness to that of a human hair). As the chemical reaction speeds up, the size of these crystals expands up to 1 mm making them fall down as rain.
When asked about the BMC having talks with Israeli experts on the subject, he begs to differ with the preference of our law makers to foreign experts. Adds Prof Rao, “They have to be familiar with our climatic conditions, local terrain and weather data before they can conduct a successful experiment”. While conducting the experiment the experts will have to understand the wind direction because once the cloud is seeded, the rainfall occurs 20 to 25 Kms downwind.
Shantilal Meckoni, an expert in the business who did it for the BMC in 2009, argues that for the cloud seeding to be effective the authorities need to plan it around April-May if you have a drought. The experiment has to be carried out ideally in the early part of the monsoon when the cloud build up is thick.
“I have done it for the BMC in 1992, 1994 and in 2009 with very good results. The problem is that the BMC wakes up very late. People have to be trained, machinery has to be put in place on time and proper coordination maintained between the civic and meteorological department. Last time around they aimed the radars at the mountains which blocked the echoes and they could not judge the cloud bank on the other side of the mountains”, argues Meckoni.
He declares that even if these things are debated now, it takes around 22 days so as to ensure proper cloud seeding takes place. Another factor that is most crucial is the presence of a Cumulonimbus cloud bank, as well as the speed of those clouds and moisture content. Meckoni too advocates the use of cloud seeding and argues that even the Israelis have been doing cloud seeding from the ground and from 60 such ground stations across the country.
- The ten prominent cloud varieties include: Cirrus, Cirrostratus, Cirrocumulus, Altostratus, Altocumulus, Stratocumulus, Nimbostratus, Cumulus, Cumulonimbus and Stratus.
- High Altitude Clouds: Above 20,000 ft -- Cirrus, Cirrostratus, Cirrocumulus.
- Middle Altitude Clouds: Between 6,000 ft to 20,000 ft -- Altostratus, Altocumulus
- Low Altitude Clouds: Below 6,500 ft – Stratocumulus and Nimbostratus (these are the clouds currently hovering over Mumbai).
- Clouds with Vertical Development -- Cumulus, Cumulonimbus (Cumulonimbus Clouds have dark bases not beyond 300 meters above the earth surface and their tops may extend up to 12,000 meters).
- In the US, Altocumulus clouds are known to generate thunderstorms and twisters.
- Cirrus clouds are thin and wispy, travel from west to east in the sky, indicate pleasant weather.
- Cirrostratus clouds are thin sheet-like clouds through which one can see sun and moon.
- Cirrocumulus clouds resemble scales of fish and hence are called ‘Mackerel Sky’.
- Cumulus clouds are puffy, appearing like floating pieces of cotton, resembling the cauliflower.