The Daily Telegraph - Features
How Reading rainmakers can bring downpours to the desert
Pioneering research in the damp English countryside aims to transform some of the world’s driest regions.
In summer 2017, a delegation of visitors from the United Arab Emirates (UAE) flew into the Berkshire town of Reading.
They had not come for a sightseeing tour, but to see how scientists at the university were progressing with the small matter of controlling the weather.
Earlier that year, the University of Reading had been awarded a US$1.5million share of a $5million fund allocated by the UAE Research Program for Rain Enhancement Science. And members of the UAE programme had arrived to observe the initial results of a project designed, quite literally, to make it rain.
To this end, the five-strong team at Reading’s Department of Meteorology has been investigating how spraying electric charge into clouds could induce rain in regions that experience very little rainfall.
The idea of effectively playing God to influence the weather is not a new one. Already in the UAE and elsewhere, older “cloud seeding” technology is being employed – a practice that generally involves spreading fine particles, such as silver iodide, salt or dry ice, into clouds to help water vapour condense and turn into rain.
The scheme being developed by the Reading scientists involves using drones to release electric charge into clouds. Dry regions such as in the Middle East and North Africa could benefit, the university says.
If it sounds like science fiction, earlier iterations have in fact been around since the 1940s, with the UAE employing cloud seeding extensively since the early 2000s.
But this week, as record floods bring chaos to Dubai, the practice has been thrust into the spotlight. If cloud seeding was being used to create rain in the UAE, then could it have caused the rare downpour in Dubai that saw a year’s worth of rain fall in a single day?
The short answer is no, it almost certainly could not. “The UAE does have an operational cloud-seeding programme to enhance the rainfall in this arid part of the world,” said Prof Maarten Ambaum, a Reading University meteorologist. “But there is no technology in existence
that can create or even severely modify this kind of rainfall event.”
No cloud-seeding operations have taken place in the area recently, he added, and there would have been no benefit in seeding clouds that were predicted to produce substantial rain anyway.
“The [weather] system was identified in our global model, which doesn’t include any inputs on weather modifications,” says Grahame Madge, a Met Office climate spokesman. “So the system at least was naturally occurring.”
In the usually arid Gulf state, where the mercury can rise to 50C in summer, planes regularly carry out cloud seeding, reportedly using salt material components.
The Reading scientists, led by Prof Giles Harrison, a bespectacled atmospheric physics expert, have meanwhile been developing their new technique, in which an electric charge is applied to make droplets stick to each other and so quickly grow large enough to fall as rain.
The technology that Harrison and his team have developed has been tested not in the deserts of the Gulf states, but in the greener English countryside. In 2020, at the University of Reading’s farm in Sonning, Berkshire, a first experiment was carried out, in which charge was released into fog using electric emitters.
The following year, further tests were performed at Bottom Barn Farm, near Castle Cary in Somerset. Here, above a verdant landscape rarely troubled by drought, unmanned aerial vehicles with specially-developed charge emitters that could release positive or negative ions on demand were launched into another foggy sky.
It was, wrote Reading’s Dr Keri Nicoll afterwards, “an important first step in determining whether charging cloud droplets might be helpful in aiding rainfall in water stressed parts of the world”.
The test flights demonstrated that the fog’s droplet size could be altered by charging, “which ultimately means that it may be possible to use charge to influence cloud drops and thus rainfall,” wrote Dr Nicoll.
She told The National, a UAE newspaper: “What we’re doing here is something that’s completely different. We are using very small aircraft, which means that things are actually much more cost effective, and we’re simply charging up what’s already there.”
Some 2.3 billion people live in water-stressed countries globally, according to the United Nations, while 3.2 billion live in agricultural areas with high water shortages or scarcity. The Reading scientists hope that research into clouds and rainfall could eventually help prevent conflict over water in such places and provide enough water for a growing world population.
The technology the Reading scientists have developed has yet to be deployed operationally. But, says Prof Ambaum of its potential future benefits: “Any small improvement to the amount of rain in arid regions will be of value.”
In the UAE, it is hoped that the innovation could help the state grow its own crops and produce fresh water.
There is a caveat though. “Note,” he says, “that if there are no clouds, then you cannot have cloud seeding. That excludes quite a lot of arid regions of the world.”
While the scientific consensus is that the cloud seeding already in use in the UAE would not have caused the floods, are there other risks associated with the practice? Dr Ambaum suggests not.
It occurs on a small space scale (the size of individual convective clouds) and short time scale (about an hour or so, the time for cloud microphysical effects to take place). “Any interventions are therefore very limited in space or time,” he says.
“This is not weather modification. We cannot change the evolution or intensity of weather systems… It is also not climate engineering: any effects are limited in time and space.”
Moreover, the materials used for cloud seeding have very low concentrations and cause no adverse health effects, he adds.
The electric charge used in the team’s research does not distribute any material into the environment at all, and as the drones used to release the charge are batteryoperated, no pollution is created from propelling the aircraft. The charge dissipates naturally.
“This means Prof Harrison and his team have developed a more environmentally-friendly method of weather modification, which could in principle operate automatically from multiple sites,” says the university.
As for the real cause of the flooding in Dubai, it seems the answer might be a more familiar one. “When we talk about heavy rainfall, we need to talk about climate change,” said Dr Friederike Otto, senior lecturer in climate science at Imperial College London.
“If humans continue to burn oil, gas and coal, the climate will continue to warm, rainfall will continue to get heavier, and people will continue to lose their lives in floods.”
In the UAE, it is hoped that the innovation could help grow crops and provide fresh water