A cloud seeding experiment carried out in Solapur metropolis, which falls on the leeward aspect of the Western Ghats and therefore will get low rainfall — 384 mm and 422 mm of whole rainfall in the course of the interval June to September 2018 and 2019, respectively — was in a position to obtain 18% relative enhancement in rainfall, which is roughly 8.67mm extra rainfall. The relative enhancement of accrued rainfall was seen over two hours after seeding the clouds. In all, the full enhancement of water availability by means of cloud seeding experiments was 867 million litres. The outcomes of the examine have been revealed not too long ago within the journal Bulletin of the American Meteorological Society.
The experiment — Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX phase-4) — was a scientific investigation performed in Solapur metropolis in the course of the summer season monsoon interval of 2018 and 2019. The main goal was to research the efficacy of hygroscopic seeding in deep convective clouds and to develop a cloud seeding protocol. The experiment used two plane for learning numerous cloud parameters and for seeding the clouds.
The examine discovered that cloud seeding is an efficient technique for enhancing rainfall in a area underneath appropriate situations. A randomised seeding experiment was undertaken to check the effectiveness of cloud seeding in producing rainfall. In whole 276 convective clouds have been chosen, and 150 have been seeded whereas the remaining 122 clouds weren’t seeded. “In our previous work we have found certain characteristics in a cloud such as the liquid water content in the cloud, the vertical motion in the cloud, which is an indicator of the growth of the cloud, will help inform us if the cloud will rain or not. Based on several criteria we know if a convective cloud has a potential to rain as all clouds cannot rain,” she says. Convective clouds with a depth of over one kilometre and prone to evolve into deep cumulus clouds have been focused.
“We must indicate that the availability of a large number of samples (150/122 seed/no-seed) is a testimony to the rainfall enhancement through hygroscopic seeding with the physical conditions set in CAIPEEX,” the authors write.
“The seeded clouds produced more rainfall than the unseeded clouds,” Dr. Thara Prabhakaran from the Indian Institute of Tropical Meteorology, Pune and the corresponding creator of the paper tells The Hindu.
Calcium chloride flare was used for seeding the clouds. A cloud seeding flare releases these particles when triggered. The seeding was accomplished on the base of the nice and cozy convective clouds and at a time when the clouds have been of their rising stage in order that the seed particles might enter the clouds with minimal dispersion. “The convective cloud bases are found at 500-1,500 metres altitude during the summer monsoon period and around 2,000 metres or more altitude during the monsoon break periods, which depends on the moisture content in the lower atmosphere,” Dr. Prabhakaran says. “Since the clouds are found at lower heights, the base of the convective clouds is warm, around 15 degrees C.”
“But cloud seeding alone cannot mitigate droughts but can help produce 18% more rainfall and partially address water requirements,” says Dr. M. Rajeevan, former secretary, Ministry of Earth Science, and a co-author of the paper. Undertaking cloud seeding as catchment-scale initiatives can probably assist in managing drought situations.
“The study was carried for two years to first study and understand the microphysics and characteristics of convective clouds that can be targeted to enhance rainfall. The work provides elaborate protocols and technical guidance to plan and conduct cloud seeding in India,” he says. The two-year examine has helped develop a high-resolution numerical mannequin that can assist stakeholders to determine goal areas, clouds that can be seeded, and an appropriate seeding technique to reinforce rainfall in an space.
One of an important findings of the examine was that not all cumulus clouds produce rainfall when cloud seeding is finished. “We found 20-25% of cumulus clouds produce rainfall if cloud seeding is done correctly. The microphysics of clouds vary widely and so not all clouds produce rainfall through cloud seeding,” says Dr. Rajeevan.
“Though the relative enhancement of rainfall was 46% as measured by automatic rain gauges, the actual increase in rainfall over a 100 sq.km area was only 18%,” says Dr. Prabhakaran.
“We estimated the cost-benefit ratio and found the approximate cost of producing water through cloud seeding was 18 paisa per litre. It was a research experiment and so we hired two aircraft from outside India for seeding the clouds. The cost will drop by more than 50% if we use indigenous seeding aircraft,” says Dr. Prabhakaran.
In locations like Solapur the place water is equipped solely as soon as in three days, the supply of further water by means of cloud seeding will probably be immensely helpful.
