Nine pilots take turns standing by, 24 hours a day, 365 days a year. As soon as they hear from the meteorologists in Abu Dhabi that they have to take off, they go. Round cylinders the size of kitchen rolls are attached to their planes, containing deicing salt for the air. Ghaith it says on those cylinders, an Arabic word that has a double meaning: ‘rain after a long drought’, but also ‘confidence in the future’.
These are the rainmakers of the United Arab Emirates, one of the driest countries in the world, and also a country that is serious about weather modification. “You have to get rid of your fear of the clouds,” one of the pilots told me to the German newspaper Die Zeit. When he was still flying a passenger plane, his task was to avoid rain clouds as much as possible. It can be risky to fly right through it. Now he flies a small propeller plane straight into the clouds, to release his load there, in the hope that the rain will fall from the sky like manna moments later. Sowing clouds, that’s what experts call what happens here.
Ever since it was founded in 1971, the leaders of the Emirates knew how important rain is: on that occasion a rain poem was even read, because a country cannot live on oil alone. Since then, water has only become scarcer. The population of the oil state has exploded, so has the use of water and underground water reservoirs are drying up quickly. Rain showers are becoming increasingly rare, as a result of climate change. Almost all the water comes from expensive desalination plants. Then making rain is sixty times cheaper, they say in Abu Dhabi.
At the National Meteorological Center of the Emirates, where six meteorologists scan the sky and especially the radars for promising clouds, the foreman tells in Die Zeit that the sprinkler planes managed to reach 98 percent of the clouds on time. It shows how much every drop of rain here matters, even if you can only wring it out of the sky with great difficulty.
Making rain is no longer something of the distant future. Know worldwide more than fifty countries a weather modification program: from Germany to Moroccoof the United States to India. China is leading the way, followed by countries in the Middle East such as the United Arab Emirates and Saudi Arabia.
But how does that work, making rain? Does it really work – that is, does precipitation eventually increase? And what are the drawbacks?
salt particles
‘There are roughly two methods for making rain,’ explains Pier Siebesma, professor of atmosphere, weather and climate at TU Delft, who has devoted his entire career to studying clouds.
The first method, which is mainly used in warm regions such as the Middle East, takes the planes about a kilometer into the air. At that height, clouds begin to form from tiny water droplets, so small that they don’t fall down yet.
‘It’s about: how do you get those droplets so big that they will fall? What you can do is add large salt particles to the air. Everyone knows: salt attracts water, it is very hydrophilic.’ Here’s why it’s so effective to sprinkle salt when you’ve knocked over a glass of red wine. ‘High in the air, the salt crystals also attract the water, causing larger droplets to grow, which eventually fall down.’
This, says Siebesma, is also often the natural way in which rain is formed. ‘In the Netherlands, this is the most important source of rain above the sea’, he assures. Also interesting: when a ship sails below that emits a lot of soot, the rain can actually be postponed. The soot particles are small, and when the water particles adhere to them, they form very small droplets instead of large ones, causing them to float high in the air.
Then the second method. The planes have to go much higher into the atmosphere, up to 5 kilometers. Of course it is much colder there, between 0 and 40 degrees below zero. You see the proof when you see the ice crystals appear on the window on the plane.
Yet the water molecules in the air are not frozen there. ‘They only freeze when they come into contact with a dust particle,’ explains Siebesma. “They have to get attached to that.” Just think of what happens when you cycle in the winter in the fog: water droplets hang in the air, but your jacket turns white from the ice that forms.
Once a few water particles freeze against such a dust particle, high in the air, then the whole thing starts to grow by itself: one water particle attracts the next, all of them freeze, until the ice particles are so large that they start to fall. By the time they arrive on Earth, they are usually thawed and rain falls.
When sowing clouds, extra dust particles are also added to the atmosphere with this second method, so that droplets in the making are formed more quickly. Usually silver iodide is used for this: its crystal structure resembles water, so that the water particles stick to it easily. But dry ice (frozen CO2) is also an option.
Vietnam War
That’s how it all started. In 1946, Vincent Schaefer, an American chemist, experimented with releasing a charge of dry ice into a cloud near Mount Greylock in Massachusetts. As a result, a thick layer of artificial snow fell. Not long after, Schaefer, who worked closely with the US military, applied for a patent on “cloud seeding.”
The US military actually applied the method: during the Vietnam War attempts were made to extend the monsoon so that the roads would remain impassable and the North Vietnamese army would have difficulty with supplies. When that came out, it sparked public controversy, prompting an international treaty prohibiting weather modification for military purposes. The American interest and investments in ‘cloud sowing’ subsequently declined rapidly.
‘There was doubt whether the costs still outweighed the benefits,’ says Pier Siebesma. “Israel has also scaled down its weather modification program for that reason.” Only in recent years has artificial rain generation returned to the fore, now mainly in the fight against climate change, as a weapon against drought.
Yet the question remains: does cloud seeding work, or does it not work? A recent US overview study mentions percentages of 12 to 19 percent extra snowfall in winter after silver iodide was blown into the air. According to the World Meteorological Organization, the increase in precipitation varies from ‘a negligible amount up to 20 percent’.
‘That is of course considerable for countries such as Saudi Arabia and Oman, where every liter counts,’ Siebesma considers. ‘At the same time, it remains difficult to prove how effective weather modification is. You hardly get above the natural noise. The amount of precipitation varies quite a bit from year to year, you see that in the Netherlands too.’
winter games
The chemical principle is plausible, Siebesma admits. But, he emphasizes: a cloud is so dynamic and unpredictable that people cannot just bend it to their will.
Sometimes something goes wrong with the influence of the weather. When China wanted to make it snow for the Winter Olympics in Beijing, there was such a snowdrift that several games had to be postponed. Yet the Chinese regime is also having enough successes: the national holiday always has a bright blue sky, without smog, because the Weather Influencer Bureau has let it rain in advance. Official documents show that the Chinese Meteorological Service also sees weather influencing as ‘a powerful tool’ to prevent disasters, support agriculture and maintain water resources.
Frank Biermann, professor of international sustainability policy at Utrecht University, is suspicious of developments in China. He is afraid that influencing the weather a could be a prelude to something much more drastic: influencing the climate. Airplanes also spray particles into the atmosphere, with the idea of reflecting the sunlight, so that the warming is slower.
‘Once people are open to the idea of consciously changing the weather, that next step, towards climate modification, becomes smaller,’ he says. And that is dangerous, he says: if intervention in the climate becomes an option, it can be used as an excuse to continue to use up fossil fuels without worry. Moreover, it can lead to new conflicts, because who then decides what climate the earth should have?
Whose are the clouds?
While that may still be a concern for the future, the influence of the weather could lead to new discussions much earlier. Countries are already arguing with each other about rivers and groundwater. Will that expand into a battle for the sky in the future?
‘Absolutely, especially in regions where drought is a major problem’, thinks Susanne Schmeier, associate professor of water law and diplomacy at IHE Delft, an institute for water education.
However, she sees that the discussions are currently mainly taking place in the select company of water lawyers. Schmeier: ‘The question is: whose clouds do they belong to? That’s not so easy. Any country could have sovereignty over the clouds over its territory. At the same time: according to environmental law, you may not seriously disadvantage other countries. For example, you may not pollute a river and allow the dirty water to flow to the neighboring country. But does cloud seeding have a significant effect on another country’s environment? As lawyers, we call on you to think about this now, before the quarrels get so high that talking is no longer an option.’
After all, the first accusations of rain theft are already a fact. “Both Israel and another country are working to keep Iranian clouds from raining,” said an Iranian military leader in 2018. That other country, that was the United Arab Emirates — with its nine pilots constantly ready to take off.