Science fiction movies are great, but sometimes they’re more fiction than actual science.
Like the new movie Geostorm.
We won’t spoil it for you, but the premise of the movie is that, after a string of colossal
natural disasters, the world works together to put a network of weather-controlling satellites into space.
Of course, then they go haywire, which leads to another string of now unnatural disasters.
So, the question is could this actually happen?
Can we control the weather with satellites?
No.
No, we can’t.
We cannot do this.
Okay, video over!
Bye!
Thanks for watching!
...just kidding.
There are actually some tiny nuggets of truth in this story.
Yes, storms are getting more frequent and more severe.
And yes, we do try to influence the weather!
But definitely not on a planet-wide scale.
The most widespread and successful example of us manipulating the weather is cloud seeding.
See, raindrops form on what are called nucleation sites, which are normally particles of dust
or bacteria in the atmosphere that water vapor condenses onto.
With cloud seeding, you add nucleation sites into the atmosphere, usually by spraying tiny,
harmless particles of silver iodide or dry ice from a generator or plane.
More nucleation sites mean more raindrops form, so you ultimately get more precipitation.
Typically, cloud seeding is done in either mountainous areas during the winter, to increase
snowfall, or in fairly arid areas during the summer, to increase the probability it will
rain over smaller areas.
It’s hard to run controlled experiments with cloud seeding, but we think it’s at
least somewhat effective!
It can increase precipitation in an area by as much as 15%, and that can really help soften
the effects of drought.
But it’s not something that can end a drought.
It’s limited by how much water vapor is available in the air, and if you’re in a
drought, there’s not a lot of vapor to go around.
So cloud seeding couldn’t start a global flood or any other natural disaster.
And it turns out it can’t stop disasters, either.
From the 1960s to 1980s, a similar cloud-seeding tactic was used not to increase precipitation,
but to try to stop hurricanes.
It was called Project Stormfury, which is awesome.
Pilots working for NOAA, the National Oceanic and Atmospheric Administration, would fly
into a hurricane and seed it with silver iodide just outside its eyewall, the most dangerous
part of a hurricane.
Supposedly, this would widen the eye of the storm.
The idea was that water would condense outside of the existing eye, which would draw moisture
away from it and form a new, wider eyewall.
And that would slow the hurricane’s rotation rate and wind speeds, and ultimately kill the storm.
The science behind this wasn’t entirely unsound, but it didn’t work.
It turns out hurricanes have too much ice in them, and not enough water vapor to condense
into a new eyewall, so seeding didn’t have a big effect.
But that’s something we didn’t know before!
And because research was always a goal of Project Stormfury, it yielded all kinds of
other insights into hurricane formation, dynamics, and forecasting.
And that played a big part in how we understand hurricanes.
It also helped to develop the logistics of hurricane research -- like, how you fly into
a huge, swirling storm and make it back with good data.
So even though it wasn’t really effective at controlling the weather, Project Stormfury
was still really useful!
Okay, so we can’t make floods or stop hurricanes — and we can’t stop hail, either.
But we have definitely tried, using devices called hail cannons.
Modern hail cannons basically just blast a bunch of noise into the sky.
The idea is that sound waves should disrupt hailstone formation before they get too big
and destructive.
And we’ve been trying something like this for hundreds of years.
In Europe, from the late Renaissance to the 1700s, people used something called weather shooting.
Basically, you’d just fire a gun into the air, because maybe the sound would do something
to the hail.
Austria actually outlawed this because people kept accidentally shooting each other.
But then in the late 1800s, the first hail cannons were produced.
They fired big smoke rings into the atmosphere, and people believed they saw some positive
effects, although they weren’t totally sure why.
They thought it may have been like weather shooting, and the sound was preventing hailstones.
Or maybe the smoke provided nucleation sites, causing water to condense into rain.
Either way, this tactic really caught on, and there were even conferences and societies
of hail cannoneers!
But after about ten years, use died down, because people noticed that, it still hailed.
The problem with all of this is that, if sound could destroy hail, then the thunder that
happens during storms would do the job for us.
Over time, people have come up with lots of ideas about how and why hail cannons should
work, but they’re still based on a faulty idea — even if some farmers still use them today.
One thing is for sure, though: All of these methods are a far cry from the all-powerful
weather satellites in Geostorm, and only one of them is actually effective.
I mean, we’re still figuring out how rain works, and we’re definitely not capable
of controlling it from space!
So if there is a natural disaster, at least it won’t have come from a satellite.
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