ABOUT ARTIFICIAL RAIN:
The need to develop and improve rain-making techniques in terms of design, operation, monitoring and evaluation by giving them a more scientific character is today's need.
This includes using computers to study cloud formations and help the rain-making operations achieve the goals of the project. The role of weather modification, or rain-making, is an important component in water resource management.
The process involved in artificial rain-making involves three easy-to-understand stages.
1) The first stage is agitation. That is using chemicals to stimulate the air mass upwind of the target area to rise and form rain clouds. The chemicals used during this stage are calcium chloride calcium carbide, calcium oxide, a compound of salt and urea, or a compound of urea and ammonium nitrate. These compounds are capable of absorbing water vapour from the air mass, thus stimulating the condensation process.
2) The second stage is called building-up stage. Here the cloud mass is built up using chemicals such as kitchen salt, the T.1 formula, urea, ammonium nitrate, dry ice, and occasionally also calcium chloride to increase nuclei which also increase the density of the clouds.
3) In the third stage of bombardment chemicals such as super-cool agents: silver iodide and dry ice are used to reach the most unbalanced status which builds up large beads of water (Nuclei) and makes them fall down as raindrops.
In planning every stage a high degree of expertise and experience is required, in selecting the types and amounts of chemicals to be used, while taking into consideration weather conditions, topographical conditions, wind direction and velocity as well as the location or delimitation of the area for chemical seeding. Several other ideas are also involved in rain making. Rockets containing rain-making chemicals can be fired into the clouds either from the ground or from aircraft.
A jet of rain-making chemicals is shot from a highly pressurised cannister directly into the cloud base, so as to coerce clouds which normally hang above mountain tops to cluster up and rain on the mountain or their slopes.
Rain-making chemicals are added to super-cooled clouds, i.e., those at altitudes above 18,000 metres, to stimulate the formation of ice crystals in the cloud or cloud cluster.
HOW TO PRODUCE ARTIFICIAL RAIN:
Artificial rain is produced by spraying clouds with substances like Silver Iodide (costly) or cheaper ones like solid carbon dioxide (dry ice) or even finely powdered Sodium Chloride. The process is called seeding.
Often there are clouds, but no rain. This is because of a phenomenon called supercooling. The temperature of the cloud might be close to zero and there might even be crystals of ice in it.
The water vapour in the cloud does not condense to liquid water. The super cooling gets disturbed by spraying the cloud with the chemicals mentioned above, using a small aeroplane for the purpose.
The `super' phenomena (cooling, heating, saturation etc.) are perverse in a sense. Very pure water when heated in a clean vessel, often does not start boiling when expected. Crystals of the photographer's hypo (Sodium thiosulphate) easily dissolve in a little water when heated. But on cooling, crystals do not separate out.
If the vessel is shaken vigorously, or if a small crystal of hypo is freshly added, then crystallization starts immediately.
Making artificial rain is a similar way of intervening in the super cooling phenomenon.
Many countries planned for artificial rain in purpose of clearing dust.
ARTIFICIAL RAIN DANGEROUS:
Ø The chemicals used in the production of artificial rain could affect climatic patterns, ecosystem, water sources and the soil, Community Water and Demographer at the Water Resources Institute (WRI)
Ø The chemicals are catalysts which, when in microscopic particles, attract water vapour that condense to form droplets of water known as artificial rain.
Ø Excessive use of the chemicals, would affect biodiversity and make the soil unproductive, besides being a water pollutant.
Ø The chemicals are most likely to affect the natural hydrological circle in the atmosphere,’ noted the expert.
Ø Experts’ comments come after the government made public its intention to import artificial rain technology from Thailand to boost power generation in the country’s depleted hydropower dams.
Ø Persistent drought in the past three years, helped on by poor water resource management, has adversely affected power production, resulting in the current power shortages and high electricity tariffs.
Ø The water expert said artificial rain would have serious negative effects on the country and would have far-reaching environmental impact, leave alone the high cost.
Ø Artificial rain would most certainly affect agricultural production and domestic water consumption in Morogoro, a major producer of staple food – rice, potatoes and maize.
Ø The technology is in use, shows that the outcome has been disastrous.
Ø In China, which invested massively in the technology, was recently a victim of bird flu that killed both human beings and birds.
Ø Just imagine, global research studies on artificial rain started 50 years ago, but we are yet to see positive results, the demographer said.
Ø The importation of the technology would add more problems to the existing ones, namely HIV/Aids, abject poverty, malaria, power shortage and new variants of diseases such as cancer. Artificial rain requires heavy financial outlay to foreign researchers and equipment, among other things.
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