All Episodes
Previous Next
Plain Text
Jan. 14, 2025 - Skeptoid
17:46
Skeptoid #971: Cloud Seeding

Cloud seeding would seem like an easy and obvious way to create rain where none existed before. Is it really that simple? Learn about your ad choices: dovetail.prx.org/ad-choices

Transcriber: nvidia/parakeet-tdt-0.6b-v2, sat-12l-sm, and large-v3-turbo
|

Time Text
Cloud Seeding: Rain or Ruin 00:14:17
Fire a few rockets into the sky, fly a small plane over the clouds and open a canister, and suddenly, thousands of feet below, raindrops start falling.
The promise of being able to control the weather to the point of having as much or as little rain as you want is so compelling as to command the intellect of our top inventors.
The only question is, does cloud seeding really work?
That's coming up right now on Skeptoid.
A quick reminder for everyone, you're listening to Skeptoid, revealing the true science and true history behind urban legends every week since 2006.
With over a thousand episodes, we're celebrating 20 years of keeping it focused and keeping it brief.
And we couldn't have done it without your curiosity leading the way.
And now we're even offering a little bit more.
If you become a premium member, supporting the show with a monthly micropayment of as little as $5, you get more Skeptoid.
The premium version of the show is not only ad-free, it has extended content.
These episodes are a few minutes longer.
We get rid of the ads and we'll replace them with more Skeptoid.
The extended premium show available now.
Come to skeptoid.com and click Go Premium.
You're listening to Skeptoid.
I'm Brian Dunning from Skeptoid.com.
Cloud seeding.
Welcome to the show that separates fact from fiction, science from pseudoscience, real history from fake history, and helps us all make better life decisions by knowing what's real and what's not.
Humans have been trying to make it rain for millennia.
We seem to always need more water, mostly to irrigate our crops, whether we're a 21st century people building a highly technological dam or people 5,000 years ago doing a rain dance.
Some 75 years ago, a researcher at General Electric discovered that he could use dry ice to seed super-cooled water droplets and cause them to precipitate out of the atmosphere as rain.
And ever since then, people have debated whether this is science or just another rain dance.
Certainly, many have taken it for undisputed science.
In preparation for the 2008 Olympics in China, the Beijing Weather Modification Office engaged in large-scale cloud seeding efforts, hoping to divert any possible rain during the Olympic Games opening ceremonies to fall elsewhere.
Beginning four hours before the opening ceremony, from 21 locations, they fired 1,100 small rockets loaded with silver iodide crystals into the clouds.
The opening ceremonies ended up being mostly dry, and many hailed the cloud seeding as a great success.
In early 2024, the United Arab Emirates, which has long practiced cloud seeding to maximize the rain their dry country receives, was deluged with intense rainfall that fell across the entire Persian Gulf region.
About 50 people were killed in flooding throughout the Gulf states.
Unlike the praise that followed China's effort, it was angry blame that was broadly leveled against the UAE for causing the catastrophic floods.
These examples, plus countless others, would seem to be evidence that cloud seeding is effective at producing rain when and where it's needed, perhaps even too much of it.
Yet the practice does not enjoy universal acceptance among atmospheric scientists.
Some say it can increase the amount of rain by 30%.
Some say perhaps 1% at most.
Results are virtually impossible to measure, since rainfall amounts are never precisely predictable, and whenever we try a specific cloud seeding experiment, it's not possible to have a control for that experiment.
Once you seed a cloud, you can't compare the results to what you would have gotten if you hadn't seeded it.
Cloud seeding's highest potential comes when atmospheric moisture is supercooled.
Supercooled water droplets are those that remain liquid water, even though they're at sub-freezing temperatures.
This happens when there is no nucleus or surface or anything around which the water molecules can crystallize.
But if they are disturbed or come into contact with anything, they crystallize instantly.
Whole clouds can become supercooled when the temperature is below freezing.
It requires the water droplets be very pure with no contaminants that would serve as a nucleus.
Such conditions are very dangerous to aircraft, as supercooled droplets instantly form ice on the leading edges of the wings.
Thus, supercooled clouds are the most obvious target for cloud seeding.
Dropping any kind of suitable nuclei into them will form ice crystals, which catch other droplets and assimilate them as well.
These then precipitate to the ground, eventually landing as snow or rain depending on the temperatures closer to the ground.
Today we typically use silver iodide crystals, or sometimes potassium iodide.
Spraying these into the atmosphere poses no meaningful environmental risk, as it's not harmful to people or wildlife, and the quantities used are relatively minute and undetectable after the rain falls, far below natural levels.
Also used is dry ice, or even plain salt, ground very fine.
When any of these particles contact a supercooled water droplet, you instantly get a tiny raindrop, which will collect any other droplets it touches.
The basic problem with cloud seeding is that no matter what you try, you cannot create water where none exists.
Seeding in a dry environment is doomed to failure because there is no water.
But seeding into a sky where moisture does exist is achievable.
However, any water you take out today is gone tomorrow.
The best cloud seeding can hope to accomplish, even theoretically, is to borrow from tomorrow's rainfall.
Bring it down today, and you'll have an even drier tomorrow.
With this in mind, experimentation sometimes focuses on places where a drier tomorrow makes no difference.
For example, coastal areas where prevailing winds carry moisture-laden clouds out to sea.
Upwind seeding in places like this aims to grab that moisture out of the clouds before it all goes out to sea.
Another related practice is called orographic cloud seeding, orographic referring to effects caused by the presence of mountains.
Cloud seeding experiments near mountain ranges try to pull the moisture out of passing clouds where it can fall as snowpack on the mountains, thus ensuring an adequate water supply of melt water to carry dependent communities through the summer.
Almost by definition, this would seem to happen at the expense of communities downwind from those same mountains, and it hardly needs to be stated that efforts to steal water from one region to benefit another is going to be controversial at best.
Thus, cloud seeding programs nearly always face bureaucratic challenges as well.
In a world that can feel overwhelming, spreading thoughtful, evidence-based content is one of the best ways to make a positive impact.
Ask your local public radio station to air the Skeptoid Files, a 30-minute radio-friendly version of Skeptoid that pairs two related episodes promoting real science, true history, and critical thinking.
And in these challenging times for public media, we're offering these broadcasts for free to radio stations, available on the PRX Exchange or directly from Skeptoid Media.
It's an easy ask.
Just send a quick message to your station's programming director.
By helping to bring the Skeptoid files to the airwaves, you'll help promote the essential skills we all need to tell fact from fiction.
Just go to your local station's website, find the programming director's email address, or just their general email address.
You can even use the telephone.
I know that might sound crazy.
It's an old legacy device that allows real-time voice communication.
I know that's weird, but hey, it's an option.
The world can feel chaotic, but you're not powerless.
When you promote critical thinking, you can help your community tell fact from fiction.
And that's how we shape a better future.
In uncertain times, spreading good ideas can make you feel helpful, not helpless.
Let's stand up for reason, truth, and understanding together.
Get them to air the Skeptoid files from Skeptoid Media, available on the PRX Exchange, and they'll know what that is.
Cloud seeding also faces opposition from people who consider it a form of geoengineering, to which they object, mainly on ideological bases.
However, the distinction should be made clear.
Cloud seeding is a short-term, highly localized activity, often targeting a single cloud on a single day.
Geoengineering, on the other hand, refers to long-term efforts to affect the climate.
Two very different types of campaign.
Cloud seeding is not a form of geoengineering.
The main challenge that cloud seeding faces, however, is neither bureaucratic nor ideological.
It's the science itself.
A 1999 paper in the Bulletin of the American Meteorological Society summarized the results of many published studies and found During the last 10 years, there has been a thorough scrutiny of past experiments using glaciogenic seeding.
Although there still exists indications that seeding can increase precipitation, a number of recent studies have questioned many of the positive results, weakening the scientific credibility.
As a result, considerable skepticism exists as to whether these methods provide a cost-effective means for increasing precipitation for water resources.
More recently, a 2010 paper from Tel Aviv University and published in the journal Atmospheric Research concluded, Reanalysis of the cloud seeding experiment and operations in Israel shows that seeding has not produced the expected enhancement in rainfall.
This suggests that seeding had little or no effect on total precipitation on the ground.
These results are in agreement with those presented by Rangno and Hobbes 1995 and the daily rainfall calculations of Kessler et al. 2006 and Sharon et al. 2008.
Those three studies mentioned are cited a lot in this field and they all come to basically the same conclusions that any effect cloud seeding might have is probably small, virtually impossible to distinguish from natural factors affecting daily rainfall, and lacking in strong experimental evidence.
But if it probably isn't very effective, what about those two popular examples at the top of the show?
Why did China spend so much money cloud seeding at the Olympics?
And why does the UAE, as well as a lot of other countries around the world, spend so many millions doing it every year?
Let's look at each case.
It had indeed been very rainy in the days leading up to the 2008 Olympics opening ceremonies, and China had long been practicing cloud seeding.
Even though this has been universally reported in the world press as a great success, that may reflect a propaganda success more than a scientific achievement.
China very much had an interest in showing off their technological prowess to the world.
Their plan was likely to succeed.
Meteorologists predicted only a 47% chance of rain on the day of the ceremony and only a 6% chance of the feared downpour during the ceremony itself.
So it was probably not going to rain anyway.
And it didn't.
For the 2024 flooding in UAE and elsewhere, it's true that they had done cloud seeding just before the rainstorm.
But they have also done it for decades, almost always without any success at all.
As far as this particular storm goes, the cause was a complex of thunderstorms called a mesoscale convective system, driven by a massive low-pressure zone in the upper atmosphere, combined with low pressure at the surface.
This storm was going to nail the area whether anyone did any local cloud seeding or not.
Its cause was major, spread over a huge area.
The seeding is unlikely to have had any impact on it at all.
So why do so many continue cloud seeding if it doesn't help?
The answer is simple.
People think anecdotally.
If it occasionally rains after seeding, our native confirmation bias causes us to remember the times it worked and forget or blur together the vast majority of the times it didn't.
Often we see governments make decisions based on popular opinion and bureaucratic debate.
Rarely do we see them make decisions based solely upon untainted good science.
And that's really the best summary of the whole science of cloud seeding.
It's plausible and it works, sort of, just not enough to make any difference or to justify the expense.
But confirmation bias, combined with laypeople's wishes and expectations, will generally eclipse the science and the decision-making process of non-experts.
Skeptoid Support and Science 00:03:25
In so many cases across all the popular sciences, you'll see this same upside-down process repeated.
And when you do, you should always be skeptical.
This episode is dedicated to the memory of Edward Peter, 2011 to 2023, a fine young fellow who put his unbounded curiosity to good work by learning voraciously every single day.
When Eddie left, he did so loved by all who knew him, each of whom was enriched by the experience, thus setting an example for us all to follow.
Take a moment to think of Eddie and how you too can be more curious to learn more and to love more.
We continue with more on how social media skewed the floods in Dubai with tons of misinformation in the ad-free and extended premium feed.
To access it, become a supporter at skeptoid.com slash go premium.
A great big skeptoid shout out to our premium supporters, including Eric Lindstrom, Stephen Rangott, Terry McGrath, and a very grateful Selena O'Brien.
I'll be hosting Bend Nerd Night once a month, every month, here in Bend, Oregon.
I'll also be hosting a whole crew of brave souls in the Bermuda Triangle this coming July on the second annual Skeptoid Adventure.
To attend one of our events or to book one of your own, come to skeptoid.com slash events.
Skeptoid is a production of Skeptoid Media.
Director of Operations and Tinfoil Hat Counter is Kathy Reitmeyer.
Marketing guru and Illuminati liaison is Jake Young.
Production management and all things audio by Will McCamblis.
Music is by Lee Sanders.
Researched and written by me, Brian Dunning.
Listen to Skeptoid for free on Apple Podcasts, Spotify, Amazon Music, or iHeart.
You're listening to Skeptoid, a listener-supported program.
I'm Brian Dunning from Skeptoid.com.
Hello, everyone.
This is Adrian Hill from Skookum Studios in Calgary, Canada, the land of maple syrup and mousse.
And I'm here to ask you to consider becoming a premium member of Skeptoid for as little as $5 per month.
And that's only the cost of a couple of Tim Horton's double doubles.
And that's Canadian for coffee with double cream and sugar.
Why support Skeptoid?
If you are like me and don't like ads, but like extended versions of each episode, Premium is for you.
If you want to support a worthwhile nonprofit that combats pseudoscience, promotes critical thinking, and provides free access to teachers to use the podcast in the classroom via the Teacher's Toolkit, then sign up today.
Remember that skepticism is the best medicine.
Next to giggling, of course.
Until next time, this is Adrian Hill.
From PRX.
Export Selection