Despite a lack of results, India remains thirsty for cloud seeding

Here’s how things would unfold if Sachchida Nand Tripathi has his way.

During winter, an ISRO aircraft flying three kilometres above ground uses its flare launchers to shoot hygroscopic (water-inducing) salts at target clouds over Delhi-NCR. Updraughts—which can reach speeds of 50 metres a second in storm conditions, but average 5-8 m/s in summer months—may be absent this time of year. But here’s hoping they’re present, because these upward air currents will help disperse the salts. The salts serve as additional nuclei for precipitation to occur.

The outcome, hopes Tripathi, is that raindrops will form as a result, showering down on the national capital and bringing temporary respite from Delhi’s air pollution woes.

…if Sachchida Nand Tripathi has his way.

The atmospheric science specialist, who heads the department of civil engineering at IIT-Kanpur, is collaborating with the Central Pollution Control Board (CPCB), the India Meteorological Department (IMD), and ISRO to use cloud seeding for artificial rain and air pollution abatement in the capital. But induced rain has a chequered history. More so in India, where the science of weather modification is a knee-jerk reaction to natural calamities. Advocate cloud seeding trials for the man-made disaster of air pollution, and you’re bound to get kaleidoscopic responses from Tripathi’s fellow experts:

“Preposterous.” — BN Goswami, former director, Indian Institute of Tropical Meteorology (IITM)

“Needs further investigation to say anything.” —Thara Prabhakaran, project director of IITM’s Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX)

“Hygroscopic seeding requires warm, tropical cumulus clouds, which don’t form in winter in the northwestern states. How will this be possible?” — RR Kelkar, former director general, IMD

“I’m not saying don’t try. But cloud seeding itself needs further substantiation.” —Saurabh Bhardwaj, earth science and climate change division, TERI (The Energy and Resources Institute)

Dissensus aside, Tripathi’s pet pilot project has other steeplechases to surmount. While it got the necessary flying clearances, the clouds, with a mind of their own, refused to show by 25 November. Adding to the delay was the availability of the ISRO aircraft, prioritised for use in the run-up to the space agency’s Chandrayaan-2 mission.

The team now waits for updated nodal clearances from the Ministry of Environment, Forest and Climate Change even as nature continues to play a straight flush in the ongoing poker game of weather modification. Meanwhile, the Uttar Pradesh government, in talks with Tripathi for cloud seeding to combat drought and air pollution in five Bundelkhand districts, is watching closely.

But here’s the thing. Even if everything comes together for Tripathi—clearances, an available plane, and suitable cloud cover—before Delhi’s smog dissipates, there remains the question of why the project should go ahead.

Sure, combating Delhi’s air pollution is important, but it can be argued that this is hardly a surefire solution to it. And as far as building a case for cloud seeding goes, that is already being done. In a far more comprehensive way. In 2017, IITM and CAIPEEX launched a three-year, Rs 250 crore (~$35 million) experiment in Solapur, Maharashtra, to test the efficacy and feasibility of hygroscopic seeding. Its results could effectively serve as a national consensus on cloud seeding.

But with the results of the IITM-CAIPEEX study still some way away, Tripathi’s efforts seem more like a shot in the dark than a silver bullet.

Seeds of doubt

Picture a form of water that liquifies at 45.8°C instead of 0°C. Water that remains solid at room temperature. The kind of water whose polymorphic crystals, when brought into contact with liquid water, catalyse it into a solid state.

If you’ve read Kurt Vonnegut’s Cat’s Cradle, you know where this goes.

Cat’s Cradle and some of Vonnegut’s short stories, with their amalgam of futurism and satire, have roots in weather modification. Specifically, in experiments at the American industrial (erstwhile) conglomerate General Electric (GE), where Vonnegut’s brother Bernard, atmospheric scientist Vincent Schaefer, and physical chemist Irving Langmuir set a precedent with cloud seeding in the late ‘40s and through the ‘50s.

From then until now, 56 countries have tinkered with clouds. To enhance rain. To increase snowfall. To suppress hail. To dissipate fog. To decrease air pollution. The choice of seeding agents has also evolved from liquid propane and dry ice to the more effective silver iodide or salts (potassium, sodium, and magnesium chloride). A private power supplier in the US state of Idaho has earmarked $3 million for seeding. In 2015, UAE, which receives no more than an average of 120mm annual rainfall compared to India’s 300-650mm, forked out $558,000 for the technology. China is building the world’s largest seeding system for rain: one powered by ground-level ‘burners’ spread over 1.6 million sq km rather than by aircraft.

Our once-spectral understanding of the stratosphere is becoming literal as scientists dissect cloud microphysics. Correction: scientists are *in the process of understanding* cloud microphysics. Because these churning clusters of aerosols, water vapour and ice crystals are gargantuan in complexity, not just size. So much so that despite some seeding operations over six decades yielding anywhere between a 5-20% increase in precipitation (on average), that statistical rule-turned-parable rears its head again: correlation does not imply causation.

“You’re not creating rain. You’re simply accelerating the process, transforming potential into something tangible, or increasing drop size in the region you want,” says meteorologist and former IITM director BN Goswami, stressing on those five words.

Emphasis here is crucial. The most simplistic of the many thumb rules of seeding science is that you need a preexisting cloud—with moisture, height, thickness, condensation nuclei, aerosol levels, and a slew of other characteristics in certain proportions—for the process to work.

In short, you can try modifying weather, but only if it lets you.

Then there are dynamic factors such as unexpected clear skies, as in the case of the impending Delhi pilot project. Clouds are always moving, and are as unique as the topographies they hover over. Take maritime clouds, for instance. Their inner workings differ vastly from those of high-altitude clouds. Additionally, they already contain traces of sea salt, which would make differentiating seeded rain from its naturally-occurring counterpart a trickier proposition. Third, consider that a warm cloud off Mumbai’s coast could have little in common with a fellow maritimer off Kolkata, and you realise how much these curveballs spin. Seeding for one cloud system won’t necessarily work for an identical one elsewhere.

With those basics established, let’s look at operational use in India.

Knee-jerk nation

In India, weather modification has almost always been a reactionary move by state governments dealing with drought or water problems. Take Tamil Nadu in the 1980s, Karnataka in 2003, Andhra Pradesh between 2003-2008, or Maharashtra in 2015. The 2003 Karnataka project (Project Varuna), had an estimated budget of Rs 9 crore ($1.2 million). In 2017, the state, under former chief minister Siddaramaiah, set aside Rs 35 crore (nearly $5 million) for another cloud seeding initiative, Project Varshadhari. From 2006-2008 in Andhra Pradesh, seeding expenses averaged Rs 25 crore ($3.5 million) each year.

In the case of Tamil Nadu, former meteorologist RG Subramanian noted that the experiments yielded rain once, in 1985—but that there was no way to link it to seeding. Karnataka’s Project Varuna was deemed a failure, considering a drive over Dharwad resulted in minimal rain in Belgaum, nearly 80 kilometres away. As for Maharashtra, the state’s Disaster Management Unit claimed a “48.3% occurrence of rain in cloud seeding occasions”, but also: “…it is not possible to ascertain increase in rainfall as it needs more monitoring in space and time.”

Whatever that last bit means.

Here’s why there’s a fundamental issue with weather modification as a ‘drought reflex’, as BN Goswami puts it.

“If you need a cloud with requisite moisture to start seeding, and that’s not there in the first place, where will you draw rain from?” he asks. “The ideal time to start is at the onset of monsoon, when clouds have adequate precipitation. Not at the end of the season.”

His reservations are echoed by all experts The Ken spoke to. Seeding could make operational sense if implemented in catchment areas instead of plains, where water collected can be put to use later, even as clouds slink across the sky.

“Seeded rain may help you cope with drought, but certainly won’t bring you out of one,” Goswami sums up. “Besides, off-season seeding also raises issues such as effect on crops. I’ve yet to see a state report addressing this.”

“If you need a cloud with requisite moisture to start seeding, and that’s not there in the first place, where will you draw rain from?”

BN Goswami, former director, IITM

Understanding the whimsical behaviour of clouds is an exercise in patience, and CAIPEEX has been devoted to the purpose since 2008. An autonomous undertaking under the Ministry of Earth Sciences (MoES), CAIPEEX is affiliated with IITM Pune and headed by Thara Prabhakaran, who says we’re yet to grasp nuances such as how aerosols—whose concentration, by the way, is affected by air pollution—impact precipitation.

“Indian studies in this context are based [merely] on satellite data. We also need dense measurements of rainfall across different locations and more radars,” she says.

Then, there’s this:

“Precipitation resulting from seeded clouds is embedded in the natural precipitation signal and separation of those are main requirements,” says Prabhakaran.

Translation: Since there’s no obvious difference between induced rain and ‘natural’ rain during a shower, a conclusion can only be drawn if you can successfully determine which is which.

And although the MoES provides technical guidance to some states on weather modification, its atmospheric science chief Gopal Iyengar sums it in one line.

“More research is needed to establish the efficacy of cloud seeding for rainfall.”

On borrowed plumes

But IIT Kanpur’s Sachchida Nand Tripathi is undeterred. Doubting Thomases or certain studies shouldn’t keep you from trying, he underlines. Neither should the wait for national guidelines by a body like CAIPEEX, which could possibly take another decade to deliver a definitive verdict on cloud seeding. Being research-oriented doesn’t have to be mutually exclusive to seeking results.

Scaling to size

China is building the world’s largest seeding system for rain: one powered by ground-level ‘burners’ spread over 1.6 million sq km, rather than by aircraft.

“When you have a fever, you’re given antibiotics. Not chastised over why you fell ill,” he says, in response to whether air pollution requires preventive, not mitigative solutions. “Ours will also be the first truly indigenous cloud seeding programme, with everything from aircraft to C-band radars being Indian. Which hasn’t been the case all these years.”

His isn’t a Make in India hangover. There’s something to be said about a country with a rain-dependent agriculture sector, but no seeding aircraft to call its own. Which is why state governments so far have floated global, not national tenders for aerial cloud seeding. CAIPEEX itself acknowledges that cloud observation and seeding is expensive, costing “Rs 10 lakh ($13,912) per mission” (each typically lasting a few hours)—and that is a conservative estimate. Tripathi says the CPCB-IITK-ISRO initiative would require Rs 15 lakh ($20,868) over two days, a better deal compared to other operations that also run predominantly on hypotheses, but cost crores.

Iyyanki Muralikrishna, project director of the Andhra Pradesh cloud seeding programme from 2006-2008, had 34 districts under his purview. The bulk of the cost (Rs 25 crore per annum), he says, was “for aircraft hiring, daily fuel, parking, and ferry flying.”

“Next were flares and ground instruments, and we had only C or X-band radars then. The doppler and mobile radars today are more effective,” he adds. And more expensive.

Bangalore-based Agni Aero Sports Adventure Academy (AASAA) was the only Indian bidder with a fleet of microlight aircraft, but even it had to rely on upgraded, imported planes and foreign pilots for projects in Karnataka, Andhra Pradesh, and Maharashtra from 2003 until 2009. Its last operational seeding exercise was in 2012, in Rajasthan.

“Because the DGCA rule in 2016 [stipulating that imported aircraft cannot be over 18 years old] became a problem. Cloud seeding isn’t a regular occurrence in any country, which means most planes modified for the purpose are older Piper Cheyennes or Beechcrafts,” he explains.

Help from outside

There’s something to be said about a country with a rain-dependent agriculture sector, but no seeding aircraft to call its own. Which is why state governments so far have floated global, not national tenders for aerial seeding

And there’s the quandary about trained pilots. A seeding pilot defies conventional aviation rules. Taking off or landing in lower visibility. Flying close to thunderstorms or updraughts, or along downdraughts or gust fronts. Manoeuvring between lurches. Looking out for ‘potential fly-ins’, because ground radars typically spot precipitation, not fully-formed clouds. Setting off salt flares at the right time, in the right spot within a cloud…

“Which is why they have to complete 3,000 flying hours in seeding operations before they can command aircraft,” says Prakash Koliwad, CEO of Khyati Climate Modification Consultants (KCMC). KCMC, IITM’s aerial seeder of choice since 2014, is the only company with three Indian pilots on its roster—and they, too, aren’t yet ready to command a seeding plane. This is where Weather Modification Inc (WMI), the world’s largest private aerial seeding company, comes in. As KCMC’s partner in sharing technology and expertise, WMI gets its own commanders to train rookies. In fact, several state operations have been piloted by WMI personnel, hired by Indian contractors.

“State operations are politically motivated, with ministers more bothered about eyeballs than serious research.”

RR Kelkar, former director general, IMD

Depending on who you ask, the tendering process is punctuated by favouritism or inflated quotes. Mukund Sriram of Agni Aviation demurs when asked about this, offering a laugh and a crumb: “Since projects are sporadic, it’s a rat race. Sometimes you don’t get tenders for reasons I can’t explain.”

But a cursory search throws light on the wrangle between Agni and IITM that reached the Bombay High Court in 2010, with allegations of a rigged bid by Agni. The company’s petition was eventually dismissed.

Prakash Koliwad denies any negative experience, but acknowledges the frequency of inflated quotes. American and European vendors also do it because the cloud seeding business isn’t really viable, he feels. Projects are few and far between relative to fleet and personnel management costs, pushing those like him to now mull expansion into the defence and surveillance sectors with UAVs (unmanned aerial vehicles).

On a wing and a prayer

In an ideal scenario, IITM-CAIPEEX could give a definitive thumbs up or down to cloud seeding—in 2019.

Starting in 2017, the institute, with the help of KCMC, kicked off a Rs 250 crore (~$35 million), three-year experiment in Solapur to quantify the feasibility of hygroscopic seeding. An American-made utility aircraft, the Beechcraft King Air C90, armed with 24 silver iodide flares on each wing, took off in intervals between July and October this year as part of the operation’s second leg. Thara Prabhakaran says the results can only be shared post-2019, after complete sample collection, analysis, and peer review.

As plane radars hum, Titan (Thunderstorm Identification, Tracking, And Nowcasting) software visualises data for meteorologists and pilots, and researchers fixate on clouds both angry and tranquil. Meanwhile, those like RR Kelkar worry about how weather modification could be deployed in the future.

“There’s a reason science and politics don’t mix,” says the former director general of the IMD. “State operations are politically motivated, with ministers more bothered about eyeballs than serious research. In the absence of a national framework, which CAIPEEX can’t construct without relevant data, who’s to say seeding won’t be undertaken by a private company that may charge for artificial rain?”

A very Vonnegut plot, this. But Sachchida Nand Tripathi has other things on his mind as he awaits his turn at the weather modification poker table.

“Of course cloud seeding isn’t a long-term solution,” he sighs, “But would you rather breathe deadly air till we stop the mess we started? Or have politicians convince you that sprinkling water from choppers can work?”

He sounds well-meaning enough, but there is no guarantee his methods would achieve any more than keeping a couple of pilots and an ISRO-sponsored plane engaged for a couple of days. Yes, Tripathi’s setup, being largely indigenous, will likely be cheaper than most other cloud seeding projects. But to achieve what?

Being a short two-day project, its success or failure will hardly be quantifiable by scientific standards. In addition, it will distract from the pressing need to implement actual measures to combat air pollution. Essentially, it will neither build a case for the technology it espouses and may prolong the problem it intends to solve. This cloud appears to have no real silver lining.

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