Rainmakers from US bring drought relief in Karnataka

The aircraft flew for 45 minutes at an altitude of 4,000 feet over Rajanukunte, 20 km from Jakkur and burnt two cartridges of silver iodide. ‘‘The cloudseeding will continue for 90 days. It is round-the-clock. We are satisfied with the technical details provided by the experts and pilots,’’ Patil said after the flight.

He said the Rs 5.65-crore project, being handled by US-based Weather Modification Inc, was a ‘‘sincere attempt’’ by the state government to use technology for the benefit of the people.

Patil said areas in interior Karnataka and catchment areas, where deficient rains have been recorded, would be targeted using this technique. He said 126 talukas in the state were facing severe drought and 73 of them had received 30 per cent less than the average rainfall.

Vice-President of Weather Modifications Inc. James Sweeny said his firm had over 40 years of experience in conducting successful cloudseeding operations in 60 countries. This is for the second time in the last 20 years that the Karnataka has resorted to cloud-seeding operations.

Cloudseeding, a technique for increasing rainfall or precipitation using naturally occurring clouds, is effective only when suitable clouds are present. To be successfully seeded, a cloud must be super-cooled, ice-free and updraft.

The clouds should possess a sustained updraft of moist air, lack natural ice and grow to heights cold enough to contain super cooled liquid water. In the case of cloud systems where the precipitation process is primarily cold, silver iodide, dry ice and compressed liquid propane or carbon dioxide is used.

Base seeding aircraft releases the seeding agent into updrafts, right under the developing storm, using a combination of wing-tip generators and burn-in-place flares. Cloud top seeding aircraft use ejectable flares and dry ice, which are released directly into super-cooled cloud top.

Once the cloud is seeded, it takes about 30 minutes for the ice crystals formed to grow to sufficient size and fall from the cloud under their own weight. As ice falls, it passes through the melting level and turns into rain.