PUNE: “Making guidelines for the future cloud seeding projects, the Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX) is going on the right path,” said Project Director, Scientist (F) at Indian Institute of Tropical Meteorology Thara Prabhakaran.
“It will be too early to speak about the success of the project as we have to complete the observations of atleast 250 cloud seeding samples before reaching any conclusion. All I can say at this stage is we are going in the right path,” said Thara.
While talking to Sakal Times here on Thursday she said, “Last year, we carried out the experiment at Solapur and collected 83 cloud seeding samples. The observations we have got few of them are positive while a few we got negative results.”
Further explaining about the project, she said, “These samples are studied statistically and physically to understand how the clouds behave before and after the seeding is done. Physical experiment uses actual observations within clouds before and after seeding and with the radar and rain gauges.”
“The physical study of the experiment includes observing the clouds before and after the seeding at different altitudes.”
“We track the seeded clouds to see whether there was precipitation on the ground or whether it got evaporated. And then if there is any precipitation on the ground, we measure it,” she said.
“This is done using the C-band radar installed in Solapur and 120 rain gauges installed in a 200 x 200 km2 area. We also have to make observations whether the seeded material has reached inside the cloud or not and what transformations are taking within the cloud. We also study the atmospheric conditions for carrying out the cloud seeding before going ahead with it,” she said.
“There is also a randomisation experiment and we have two to three randomisation cloud samples collected per flight. It is a very laborious task and this year, we have to finish 200 samples,” she said. “Currently, we are stationed at Solapur and carrying out the observations through the specially designed aircraft in the radius of 100 km from Solapur. We have a sanctioned budget for the experiment and spends nearly Rs 10 lakh per day. We fly for two to three hours daily depending on availability of suitable clouds,” she said.
WHAT IS CAIPEEX?
“We study the weather conditions first to see if suitable clouds may develop for cloud seeding. Generally, the experiment is done during monsoon period as there is ample moisture in the atmosphere and there is natural formation of convective clouds. Most of the experiments held before are of operational nature, but this is for the first time we are doing a scientific seeding study,” she said. “We study the cloud and know how much water it contains and what kind of updrafts are there,’’ she added.
“We release flares near the cloud base which contains seed. The flares when burnt produces the particles to act as cloud condensation nuclei. These particles attract water vapour. With an aircraft that have various instruments on board goes inside cloud and monitor the rain droplets and cloud droplets. We will measure where exactly the droplets are formed after seeding and when does it go down on the surface as rain drops,” she said.
“The study will help in making better numerical models for monsoon prediction. While conducting the experiment we choose warm clouds with temperature higher than 0 degree Celsius to target for hygroscopic seeding. We use Glaciogenic seeding in clouds that can form ice at colder temperatures and ice melt as it falls down and make rain,” she said.