Is Cloud Seeding Good, Bad, Or Ugly?

The Chinese Communist Party celebrated its centenary on the 1st of July, 2021. For such a celebration, clear skies and clean air would be ideal. For the capable nation-state, however, one needn’t hope against the whims of the weather. One can simply control it instead!

A recent paper released by Tsinghua University indicated that China had used cloud seeding in order to help create nicer conditions for its 100-year celebration. Weather modification techniques have been the source of some controversy, so let’s explore how they work and precisely what it was that China pulled off.

What Is Cloud Seeding?

The basic principle of cloud seeding, using chemicals as nucleation points for precipitation in clouds. Credit: Naomi E Tesla, CC-BA-SA-4.0

Cloud seeding is a relatively simple process that aims to induce or vary the amount of precipitation that falls from the sky. Various substances can be dispersed into cloud formations, serving as nuclei for ice crystals or water droplets to form. Once reaching a certain size and weight, these then fall to the ground as rain or snow or other forms of precipitation.

A significant variety of methods exist, with silver iodide being a popular choice. This is as the substance bears a similar crystal structure to that of water ice, allowing it to serve as a nucleation point for condensation, helping to form snowflakes in clouds. The material can be delivered directly via aircraft or rockets, or released into updraft airstreams from generators on the ground.  Actual amounts of chemical used are quite small, with minimal polluting impact.

The technique is useful, as it allows some level of control over precipitation. It can, in theory, be used to cause clouds to rain over an area, to either make an area wetter when desired, or to remove water from the atmosphere so that later days will be drier. Cloud seeding does rely on the presence of moisture already in the cloud system, however; it cannot cause precipitation where no atmospheric water exists.

China’s Applications

As reported by the South China Morning Post, the recent research document indicated evidence that cloud seeding had been used in the days leading up to the centenary celebrations. In the lead up, local air pollution levels were high, despite reported efforts by Chinese officials to close heavily-polluting factories ahead of time. Low winds in the area were cited as a possible complicating factor that was preventing the pollution from clearing.

Researchers claimed that a cloud-seeding operation had occurred for two hours on the day prior to the ceremony, with reports of rockets being fired into the sky from residents in the area. The paper asserts that the rockets spread silver iodide particles into the clouds to create rainfall ahead of the event.

The paper also indicated an improvement in PM 2.5 particulate levels, significantly improving the air quality readings from “moderate” to “good” in the affected area. The paper notes that they found little evidence of anything other than artificial rainfall that would be responsable for the better air. Easily-accessible online data from the area is difficult to compare, as the results are averaged over a full 24 hours. However, a small drop is noted from June 29 through to July 1.

Often referred to as “blueskying,” the weather modification method has been used in similar ways before, such as during the 2008 Beijing Olympics. In fact, China’s history with cloud seeding goes all the way back to early efforts in 1958 to help bring rains to agricultural areas in the north of the country.

Since then, China has invested heavily, with the country’s weather modification organizations reportedly employing over 35,000 people, including everyone from meteorologists to simple farmers, charged with firing shells into the atmosphere bearing silver iodide or other seeding agents.

So What’s The Problem?

A Royal Malaysian Air Force plane loads up with water and sodium chloride for cloud seeding, hoping to generate rain to combat smog from forest fires. Credit: Getty Images

There are plenty of benefits to getting rain on command – water for crops, rain to help remove particulate pollution from the air, or even just keeping rivers flowing in periods of drought. However, the practice of cloud seeding has drawn some controversy, due to the potential for either deliberate or unintended negative outcomes.

China has already put forth bold plans, and hopes to one day divert water vapor in the skies above the Yangtze River Basin to fill the drier Yellow River basin in the country’s north. The hope is to shift up to 5 billion cubic meters of water annually to where it’s needed.

However, projects on such a large scale could easily effect water that would typically fall in other regions. Fears are that south-east Asia and India could be affected, if rain is directed to fall where it suits China best instead. Outlets like the Times of India openly speculate that this could have serious affects on India’s rainfall, and thus its vital water supply.

Cloud seeding already has a history of being used with less-than-pure intentions in the past. United States forces infamously implemented Operation Popeye during the Vietnam War, a cloud-seeding operation with direct military goals. The project hoped to maintain rainfall on the strategically-vital Ho Chi Minh Trail, such that the dirt roads would turn to mud and break the Vietcong’s supply lines. The project began in 1967 and lasted until 1972, with pilots seeding clouds with silver or lead iodide from canisters spewing chemical-laden smoke into the air.

Cloud seeding equipment as fitted to a Piper Cheyenne II light aircraft. Credit: Getty Images

The results were mixed, and secrecy around the project means that it’s hard to determine exactly what Operation Popeye achieved. However, after it was revealed to the public in the 1970s, it quickly led to the establishment of the Environmental Modification Convention, which aimed to ban the use of weather modification for military aims.

It’s also been cited that cloud seeding may have been used in the wake of the Chernobyl disaster, aiming to cause rain to help remove nuclear fallout from the atmosphere before the radioactive cloud reached Moscow itself. The assertion has repeatedly been denied by authorities, but it’s another example of how weather and rainfall could be manipulated for better or for worse.

Meanwhile, small and large cloud seeding projects go on around the world on a regular basis. Some are for research, others hope to break droughts, and some even want to fight fires.

A Controversial Technology

Like many technologies, cloud seeding is as controversial as the way in which it is used. The problem, however, is that the results of cloud seeding are so diffuse and difficult to quantify that it can be hard to police or even accurately measure its effects.

It’s entirely possible to fire a bunch of chemicals into a cloud, and measure how much rain falls in the immediate aftermath. The cloud may have rained anyway, and controlling for this effect is difficult because cloud seeding relies on the humidity being in the air in the first place. The downstream effects are similarly murky. A country may run some experiments or programs to seed clouds in their own territory, but proving that this causes a drought 1,000 miles away would be incredibly difficult.

Regardless, humans have always wished to control the world around them, and weather modification is just another way to do just that. With any technology, expect to see it used and misused in equal measure going forward. Only when we truly understand the effects, can we make sure that we see more of the former, and less of the latter.


34 thoughts on “Is Cloud Seeding Good, Bad, Or Ugly?

  1. Like all scientific discoveries/accomplishments, cloud seeding should be used only when appropriate. Exceptionally bright blue LEDs have become the modern day bane of consumers because a single scientific discovery/accomplishment has been used very irresponsibly. Plastics have been likewise been used irresponsibly and now it’s polluting the planet to the point where microorganisms are evolving to break it down.

    In short, play with fire and you will get burned.

    1. Electrical tape is a great solution to those stupidly bright LED – just prestrech it to the translucency you need – it gets gradually more transparent the more it is stretched – in my experience very controllably without loosing its adhesive properties (will take some trial and error no doubt). Its available in so many colours something that looks tidy on your device isn’t hard to find.

      Would be nice if device makers realised you don’t want bright enough to be easily seen in the noon day sun on nearly any device – almost everything lives in a house, or is hand held so you can tilt/shade it to see the status lights, so the LED’s really don’t need that much punch, something between bright enough to be clearly visible in a normally lit to dark room is sufficient…

      1. I bet someone could come up with an LED package with a simple auto-brightness circuit built in. I think even a simple photoresistor in series with the actual diode might work. They’d be drop-in replacements, with no excuse for manufacturers not to use them.

        1. Avoiding a feedback loop might be a little tricky, and its bound to cost more, plus you have to make it flicker stupendously fast if you want it to be embedded everywhere – the slower flickering rates things like some florescent bulbs and dimmable LED have are not good for some folks (bothers me when I already have a headache, but for some it would be much much worse)…

          Its a good idea though, would be great if they did implement such a feature…

          But personally I’d be happier going back to the dimmer LED of my childhood where just a reasonably well lit room could wash the common ones out enough you needed to cup your hand over them to be 100% sure – when its your power on, HDD activity type completely unimportant light 99.9% of the time there really isn’t a need to make it disco rave levels of obnoxious, when you need to see it you can easily enough. But I don’t need to be able to read my book on the other side of the room at night just from the glow of the standby/on light (I’m looking at you USB3 hub, KVM, and especially you monitor with the large light pipe and quite possibly multiple LED!!!). That level of illumation should be for the ‘oh bother’ something really important has gone wrong warning lights, not the basic status lights…

        2. You don’t need to go that far. In general, most indoor devices don’t need to be extremely bright. Simply using a 10k resistor instead of a 300ohm will turn that retina searing bright blue into a simple blue indicator light.

      2. Especially bad design award should go to those who make devices which are supposed to be near bed at night so bright.
        Medical devices are particularly bad in this way.
        CPAP machine, base stations for devices like pacemakers and wearable defibrilators, etc.
        The pacemaker base station, with big light panels I could read by goes in a cardboard box.
        (Means I can’t see if it ever has an error, but at least I can sleep.)
        CPAP machine is harder – needs air flow and a hose to the bed.

        Devices with lights that change regularly are even worse.
        Try to spend a night in a hospital. The Christmas lights on all the machines make sleeping difficult,
        but even worse was the screen saver on the medical computer screen. It keeps changing the level of light it gives out.

        We are tuned to alert to changes/motion more than steady inputs. So a screen which suddenly gives off more light is more likely to awaken than being in a steady lighter environment. Turning the screen away from the bed doesn’t help much –
        the reflected light is enough to trigger/allert the would be sleeper.

        The nurses kindly turned off the monitor when I asked.
        But hospitals should design their system to be dark at night.

        Sleep is essential to health. Poor sleep in hospitals contributes to worse health outcomes,
        longer stays, more expense, etc.

        So something as seemingly minor as how you configure your hospital’s screen saver
        could save lives and improve the hospitals bottom line.
        (Make it give a steady light level, keep it darker at night.)

    2. I’m glad you sorted that out. Imagine how many HaD readers were on their way to dump truckloads of plastic in the oceans! I know I won’t do it anytime soon.

      Now, if you had written that in Hindi and Mandarin and Indonesian and Portuguese…..

  2. I’m glad you mentioned sodium chloride seeding. That concept was discovered in South Africa around 30 years ago.
    And also mentioning that every drop of precipitation starts with a nucleotide particle.

  3. Cloud seeding as ethical – I think it is along the same lines as damming rivers that cross international borders or depleting ground water via wells. The law of unintended consequences seems to be hovering closely over this one.

    The cloud seeding graphic (which appears to be from wikipedia) uses an A-10 Warthog ground attack airplane. The designer probably grabbed the first drawing they found. I’m pretty sure no A-10s have ever been used for this. Searching did not turn up any references. Seems totally random.

  4. What about using particles to reflect sunlight for a cooling effect? Weather modification shouldn’t be a question of “what happens?” It should be answers of “we know what happens, by how much, and when and where best to use it.”

    We have become the dominant organism on this planet by modifying our environment and we cower at benign attempts to do that. I’m not saying test a nuke to destroy a hurricane, but using some of the ideas of NOAA we can try things to see what the overall effect is.

    Our ability to mitigate what climate change may bring won’t be entirely fought on not driving or buying an electric car. It will be what we can do to lessen the forces of nature that cause damage or to bend it to our will to bring water to areas that are in drought.

    1. Every major change Humanity has made to the environment has had so many consequences that were not at all predicted, or worse were expected but needs for profit in the moment meant damn the consequence that isn’t our problem… Its about time we learnt to be a little more careful before jumping into major new artificial changes in how things are done – putting back what should always have been there if we didn’t bugger it up already on the whole can’t easily go wrong (as the natural world will self regulate given a chance), but new major changes where we try to play god and regulate large areas of the natural world very artificiality should be taken very carefully…

      Also If I need all the water I can get out of the air above me and have the ability to drag it out what happens to you poor smucks upwind and the ecology of the entire region if I take it all – weather modification by such steps is insane as its not easy to predict at all what the effects will really be over a wider area, and its far too easy to say its working for us who cares – international good will is rather a myth (in some places much more than others), and even in the same nation, speaking the same language and from the same cultural backgrounds there is enough ‘who cares its only x’ and ‘out of sight out of mind’ sentiments flying around at times…

      Carefully planned tests of such things after a great deal of modelling to predict the outcome as best as possible, and constant monitoring to see how bad those educated guesses actually turn out to be might be a good idea, but not really possible – you would need pretty much global co-operation for any hope of getting proper data (or to conduct ‘tests’ that were so large scale and sustained they aren’t tests but jumping in blindly to doing it and hoping it all works out – which we really don’t have a great track record of…).

  5. There is another form of weather modification that needs attention, the flight of jet aircraft. 9-11 was a fortunate experiment that shows what effect they have on weather. An article in Pop Sci decades ago expressed concern about the loss of crop growing sunlight over the corn belt which lies under some of the most traveled airspace on the planet. A year plus ago gave us again skies that were uncluttered by the sky-slug’s ugly trails. Time to get the saltshaker out. We can do without all the germs and virus spreading around from this time on out.

      1. I think [echodelta] meant that there was a noticeable reduction in air pollution when the US airlines shut down for a few days afterward.

        But yeah, it does seem like that is what [echodelta] said…

  6. Well, continuing to burn fossil fuels and mine the crust for minerals has some pretty well proven negative consequences, yet nations still seem intent on pilfering the whole planet for its industrial raw materials. Perhaps the bad and the ugly of cloud seeding are indeed well known by the CCP, but it may be that at this point the risk of doing nothing is more damaging than the consequences of active manipulation.

    Anyway the Chinese agricultural economy seems to be highly productive, and other nations should take notice and verify if cloud seeding has anything to do with that success.

  7. PLS remember, seeding is an act of taking water at your location rather than letting Mother Nature put it further downwind that it would have been on it’s own. And mankind can argue that up to the level of legal disputes.

    A greater oversight is needed…. or none at all so just don’t do this to your neighbors. It takes a lot of energy to what nature is trying to do.

  8. Th USA seeded the Ho Chi Minh Trail with lead iodide? It’s not the most evil thing done during that conflict, but it’s pretty damn evil to spray fine heavy metal particulates into the atmosphere AND water simultaneously.

Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.