Sunday, Sep 21, 2003
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By B. Chandrashekhar
According to them, cloud-seeding operations are not experiments but a proven scientific process. Interacting with The Hindu at the Bangalore airport and at their base at the Jakkur airstrip on Friday, they outlined the process and spoke about the chances of rain as a result of cloud-seeding. The cloud-seeding would take place for the next 90 days after measuring the required parameters of the clouds available from time to time, they said.
The Principal Aviation Consultant of Agni Aviation, K.T. Sebastian, said cloud-seeding would be of two types -- base seeding and top seeding. The ideal conditions for the success of the operations were thick clouds with 0 to -5 degree Centigrade temperature on their surface, he said. Cumulus clouds would be most ideal, he explained.
"Larger the cloud, greater the chances of rain,'' he said. Besides, the wind speed should be about 10 knots per hour. Cloud-seeding would do cloud condensation ultimately resulting in rain, he said. Flaring of silver iodide and sodium chloride from the top and base of the cloud would condense the clouds, he said. The ideal time for the seeding was between 3 p.m. and 8 p.m. in the region, he said.
The crew conducting the operations were experienced about 18 to 20 years in cloud-seeding. Seeding of clouds would also result in condensation of large strata of clouds into a rain-bearing cloud, he noted. Though cloud- seeding dated back to the 1880s, serious efforts began from 1946-47, he said.
The chief pilot of the three aircraft conducting cloud-seeding for Karnataka and Andhra Pradesh, Paul Meier of Weather Modification Inc., stated that about 60 countries were conducting cloud-seeding operations in the world. In the U.S., 29 out of 51 states had licensed cloud-seeding clubs, he said. In India, cloud-seeding was on from 1983, when it was done for the first time in Chennai.
Bulk of the funding for cloud-seeding operations in the US was being done by insurance companies and the government contribution was very little, he explained. The rate of success of cloud-seeding or the enhancement of rain was recorded 15 per cent in cold climatic countries and 20 to 25 per cent in warm climatic countries, he noted.
Asked to comment on the success rate of operations in Karnataka so far, Mr. Meier said though it was not measured scientifically it was reasonably good. Further, he explained that seeding on the clouds in the premature and mature stages at a height of about 3,000 feet would be most useful.
Effect of cloud-seeding could not be known in a short period. It would require at least five years to study the proper impact, Mr. Meier said. Citing an example the enhancement of rain was recorded 18 to 19 per cent in California in the US, where the cloud-seeding was being done for the last 20 years.
The meteorologist of Weather Modification Inc. at the radar station at Jakkur airstrip, Bill Thomson, said it would take 3 to 4 days to survey the pattern of clouds before serious cloud-seeding could begin. The telemetric equipment fixed on the aircraft would enable it to identify the clouds chosen with the help of the radar station for seeding. It would take almost 12 hours to get the reports about the cloud-seeding done, he said.
In all, 73 mandals in Anantapur, Chittoor and Cuddapah districts have been chosen for cloud-seeding.
However, a few officials of the Weather Modification Inc., said on the condition of anonymity that the Andhra Pradesh Government was yet to give them topographical maps of the area chosen of cloud-seeding.
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