The worst floods in Pakistan's history are devastating its already fragile economy, adding further instability to the troubled nation.
This is a question for the forum to decide whether the recent rains causing super flood were Artificial.
Read Article
How is artificial rain produced?
R.Narasimhan, Chennai
ANSWER 1: 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. 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.
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. 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.
The Hindu S&T desk
* * *
ANSWER 2: 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.
While Dubai was burning in summer heat an artificial relaxation was arranged by the Government of Dubai. Find it on AltafSayani.com
Artificial Rain in Dubai
By Altaf Sayani on July 7th, 2008 in Interesting | No Comments
Share24
Dubai residents got a nice rain which helped to get cooled in this summer.
Here are the few snaps
Can you believe?
It was an artificial rain done by the Meteorological department at the National Center of Meteorology and Seismology (NCMS) to remove the air pollution on Dubais atmosphere.
It is called Cloud Seeding a latest technology to customize weather. Could 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. The usual intent is to increase precipitation, but hail suppression in also widely practiced. Silver iodide and dry ice are the most commonly used substance in the cloud seeding
An aircraft putting dry ice on clouds which makes artificial rain.
/././././.
SMIQBAL
