As cloud seeding catches on in times of climate change, more research holds the key

An aircraft poised to enter dark clouds – and spray chemicals to produce rain. Sounds magical — that’s the image often associated with cloud seeding. In reality, it is much more hard work and long hours of research and painstaking data collection.

Increasing drought and water scarcity in India and the erratic monsoon due to climate change has prompted governments into thinking of cloud seeding as an option to create artificial rains.

Cloud seeding introduces particles of salts like silver iodide and chloride into the cloud using a special aircraft. These salt particles act as nuclei on which cloud droplets or ice particles form, called “cloud condensation nuclei” or “ice nucleating particles”. The seeded clouds make modifications within the cloud, leading to the formation of raindrops.

The enhancement of rain at the surface can potentially benefit all the sectors that depend on rainwater, including agriculture, electricity and the environment.

While research on cloud seeding began in India in the 1970s, it has received a boost since 2018 with the Union Ministry of Earth Sciences investing in data collection and experiments. Research by the Indian Institute of Tropical Meteorology (IITM) in Pune, especially over the last two years (2018 and 2019) will result in a white paper with the scientific facts on the ground for cloud seeding, should states wish to take it up as a measure to increase rain water.

This will include guidance on what should be the best practices and help states take decisions on cloud seeding, according to M. Rajeevan, secretary, Union Ministry of Earth Sciences. While the Ministry has no plans to have a national programme on cloud seeding, it has already spent Rs 45 crore on research in 2018. In 2019, the work will continue, costing a total Rs 100 crore.

“Cloud seeding or weather modification hasn’t yet been developed very well in India. Our methods need much more improvement,” said Rajeevan.

However, in the context of climate change, cloud seeding could increasingly become a viable option. “We really want a solid scientific way of carrying it out, so that people will not be fooled by private players,” he added.

This is also something that the World Meteorological Organization (WMO) has spoken of in a 2018 report. While many countries have been practicing cloud seeding, not all seeding efforts are being undertaken after a rigorous analysis, states the report. The WMO also warns of organisations that try to take advantage of desperate situations by giving unfounded promises.

Most cloud seeding activities are being undertaken primarily in response to cries of water shortages affecting agriculture and other societal needs, found a 2017 survey of WMO members involved in weather modification. Some agencies have realised the value of cloud seeding in augmenting the routine water supply, while others have been using the technology to redistribute precipitation in order to supply water to urban areas or to suppress wildfires.

Cloud seeding: The Indian context

The IITM has initiated a national level campaign designed to make progress in aerosol and cloud microphysics observations over the Indian region, which can be used to propose guidelines for cloud seeding. The project, called the Cloud-Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX), will be focussing on aerosol-cloud-precipitation interactions in the pre-monsoon and monsoon environment, said Thara Prabhakaran, who is the project director.

“These observations could be instrumental in improving the representation of cloud processes in weather and climate models for the understanding of weather modification and its effective implementation,” she said.

When cloud seeding research started in India in the seventies, the initial focus was on warm cloud seeding as it was observed that the atmosphere had predominantly warm clouds, said Prabhakaran.

“Several experiments were conducted in the Baramati region, and the results indicated that the seeded clouds had an advantage in the initial development of precipitation as illustrated in the hypothesis for seeding. With the understanding that these observations are vital for the verification of the effect of cloud seeding, IITM began focussing on various observational aspects to illustrate the pathways through which rainfall could be made from seeded clouds,” she added.

While early field experiments used an aircraft for salt seeding, the science has progressed much with advanced seeding material and new observation technology comprising radars and aircraft instruments, she said.

The CAIPEEX research began in 2009 with airborne observations of clouds, leading up to experiments with pulverized salt and potassium chloride flares in 2010 and 2011. This is for the first time that such a scientific experiment was conducted in convective clouds over the tropics.

However, those experiments failed to provide statistically significant number of samples.

As part of a multi-phase experiment that started in 2018, the IITM has established an observational facility at Savitribai Phule Shikshan Prasarak Mandal’s N. B. Navale Sinhgad College of Engineering (SPSPM’s NBNSCOE) in Solapur, Maharashtra, Prabhakaran said. The dual polarimetric C-band radar positioned in Solapur can monitor clouds and passage of rain over a 200-km radius from Solapur. IITM has also set up a rain gauge network of over 120 gauges to record the rainfall received at the surface.

A seeder and a research aircraft equipped with instruments are used to seed clouds and document the changes in clouds leading to rainfall. In the 2018 experiment, IITM used calcium chloride flares for seeding. More samples are being collected for the 2019 experiment to formulate guidelines for seeding. The airborne experiment for 2019 will also be conducted from Solapur, in September 2019.

Research in cloud seeding has received a fresh impetus from this laboratory at Solapur for aerosol-cloud interaction studies. It is equipped with several state-of-the-art instruments, which give a clear idea of the day-to-day variations in cloud and aerosol properties. “We use these observations to design the experiment and test hypotheses,” said Prabhakaran.

Since 2018, regular observations have been made and 82 cloud samples have been collected. “We need to collect 250 samples for the control experiment. Airborne observations will be conducted this year to collect more samples. With just a few samples it is too early to give the results of the experiment. After the randomisation experiment with enough samples, protocols for cloud seeding in the rain shadow region of the Western Ghats would be prepared. In some countries, only after several years of observations have these many samples been collected. We are trying our best to collect enough samples in a short period with a well-planned experiment,” she explained.

A complex experiment

Cloud seeding is a complex experiment with a lot of logistics involved, and everything has to work in tandem to get the best results, Prabhakaran explained. “The major challenge before our team is to document the processes leading to precipitation after seeding. This is important for the physical (scientific) evaluation of the samples. The major beneficiary of cloud seeding would be water resources, but plans for implementation and evaluation have to be well thought out much before the experiment,” she added.

Not all clouds can be seeded. Researchers need to test for certain criteria, and carry out physical and theoretical experiments to illustrate the possible effect of seeding, she pointed out.

“Scientific cloud seeding studies require suitable infrastructure to select, seed, monitor clouds and evaluate precipitation enhancement,” said Prabhakaran.

The chain–from the process of formation of raindrops to the increase in surface rainfall–is difficult to document, increasing the complexity of the experiment.

The approximate cost of each seeding mission is around Rs. 10 lakhs. However, cloud seeding technology is not readily available in India and studies on several fronts, from seeding technology to implementation, are needed, she said. The aircraft and other necessary infrastructure are hired from other countries.

Over 50 countries use cloud seeding for improving the prospects of weather modification. There are several claims regarding the use of various techniques for weather modification for rainfall. Not all methods have been tested or proven scientifically, she pointed out.

Opportunity for entrepreneurs

Private players too have eyed cloud seeding as an opportunity and developed some expertise with the help of organisations abroad. When his software company folded up after the World Trade Centre bombings in 2001, Prakash Koliwad, an engineer, went back to his agricultural roots in Ranebennur taluk in Haveri district. For two to three years he worked the land but couldn’t sustain it as the crop failed owing to drought. He then took up hydrofracturing as a business, and later in 2003 when the Karnataka government under chief minister S. M. Krishna took up cloud seeding, he decided that it was what he had wanted to do all his life.

In 2009, he set up the Khyati Climate Modification Consultants (KCMC) LLP, to help farmers get more water. This is one of the better equipped private players in India. KCMC partners with Weather Modification International, a U.S.-based company. In 2017, Prakash Koliwad’s belief that cloud seeding was the answer to the future problems of water scarcity was reinforced by a successful effort in Karnataka.

“It was fantastic and the state government took it up seriously with a team dedicated to this endeavour, followed up, gave scientific advice and also studied the impact of cloud seeding,” Prakash said.

An evaluation report prepared by experts, including some from IITM, said cloud seeding had increased localised rain by 27.9 percent. There was much scepticism as the earlier experiments with cloud seeding in the state in 2003 and 2009 hadn’t delivered much. The 2017 success, however, prompted the state government to continue with the programme. The company will undertake cloud seeding programmes this year and the next all over the state.

In Maharashtra, the state government has allocated Rs 30 crore for cloud seeding this year after last year’s severe drought in the state. In 2015, KCMC conducted cloud seeding for the first time in the Marathwada region. An official said Rs 27 crore had been spent on cloud seeing that year and that there was a 28-mm increase in the rainfall in Marathwada. Last year the government didn’t do it as there were good rains in the beginning–the dry spell came later.

The procedure for cloud seeding needs to be kick-started in March or April as there is a tendering process involved and approval has to come from various government agencies. It takes about a month or two to get everything in place, said Prakash.

Cloud seeding is considered a contingency measure. In reality it should be a continuous effort, he said. Cloud seeding experiments are often scoffed at as the yields may not always be tangible. The technology, using flares and limited amount of chemicals for spraying, is now more sophisticated, he added. KCMC owns an aircraft modified for cloud seeding operations, and has leased four aircraft from the USA. States like Gujarat, Uttar Pradesh and Madhya Pradesh have also approached it for cloud seeding. It also assists IITM in research activities.

A scientific basis for cloud seeding

One of the reasons why the Ministry of Earth Sciences is bringing out a white paper is to lay down the scientific basis for cloud seeding. According to Thara Prabhakaran, there are a number of ideas that hold out rain enhancement promises floating around. However, several of them do not have any scientific evidence.

India needs more research and documentation on the efficacy of cloud seeding through observation and numerical experiments. “If we have no observations of rainfall using well-calibrated radars and rain gauges, it will be difficult to talk about success or failure. It matters to each one of us how much rain reaches the ground. For example, if the environment is too dry, the rain that is developed may evaporate while in the atmosphere itself. We need to document the environment (moisture, winds, temperature, etc.) in which these clouds are growing, understand the background aerosol conditions and their physical and chemical properties, etc.,” she said.

The Ministry of Earth Sciences, answering a question in the Lok Sabha in 2016 had clarified that “artificial rain making techniques involving cloud seeding cannot be used for bringing rain clouds to rainfall deficit/drought areas. These techniques can only induce potential pre-existing clouds with adequate cloud droplets, to produce enhanced quantum of rain.”

There is great curiosity about cloud seeding as a means of improving the rainfall situation and mitigating drought, but the belief that cloud seeding is a panacea for all situations has to be ruled out. Governments will also have to invest in water conservation, water management and plan for contingencies when water becomes really scarce. They should not be looking to cloud seeding to solve all water-related problems.

However, the IITM experiment and the white paper (when it is published) will go a long way in providing the research efforts a scientific basis on cloud seeding and its use, and stop the generation of wild and unrealistic expectations. This is especially important in these times of climate change and massive weather fluctuations.

 

Banner image: Aircraft used for research and seeding. Photo courtesy the Indian Institute of Tropical Meteorology (IITM).