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  • As devastating droughts threaten regions across the world,

  • scientists have proposed a solution that sounds like science fiction.

  • If the water doesn't come during the winter in the form of snowfall, and doesn't come during the spring in the form of rain...

  • what if we just make it rain? Literally?

  • While this may seem like a far-fetched fix, this idea is actually based on technology that's been around since the 1940s.

  • It's called cloud seeding, and it is what it sounds like:

  • Tiny particles are released into the air, either by an aircraft or an automated machine.

  • This technique relies on the answer to one key question: where do clouds come from?

  • The simple answer is that clouds have nuclei, but not the kind that atoms have.

  • Water evaporates into the atmosphere as part of the water cycle.

  • That evaporated water accumulates around micro-scale solid or liquid particles made of dust or pollen...or even bacteria.

  • These are called condensation nuclei.

  • As more and more water vapor clings onto a condensation nucleus, it starts to form a cloud droplet.

  • Once the droplets get big and heavy enough, they fall from the cloud in the form of precipitation

  • that can be rain, snow, even hail!

  • The scientists who came up with the idea of cloud seeding assumed that the limiting factor to how big clouds get

  • or how likely it is they'll precipitate is these condensation nuclei.

  • So, they decided to add some.

  • They chose silver iodide particles because their crystal structure is assumed to be very similar to that of real ice,

  • providing a scaffold for water to cling to.

  • Adding these particles to growing clouds helps water vapor freeze around the nuclei at higher temperatures than it would naturally,

  • making precipitation come faster.

  • And after its invention, cloud seeding was widely adopted.

  • It was put to work by the U.S. governmentmost notably during the Vietnam War, with the goal of flooding enemy supply routes.

  • But in the 70s, the UN adopted a resolution to ensure that all its member states would only use weather modification

  • like cloud seedingfor peaceful purposes from then on.

  • So, it may sound like a simple and effective solution:

  • Just make more clouds to make more rain, right?

  • But there are four main pitfalls that mean we gotta switch the faucet off on that excitement.

  • One: we still don't really know if it works.

  • Or if it does work, how effective it is.

  • See, once you've seeded a cloud, it's tough to say how much precipitation that cloud would have yielded if you didn't seed it.

  • One recent study DID find that some seeding produced snow where it would not have fallen otherwise...

  • but the amount of snow was negligible.

  • And in areas where precipitation was expected, it's still hard to say if seeding made a difference either way

  • in what would have fallen naturally.

  • We also don't actually know HOW water vapor forms around condensation nuclei into cloud droplets in the first place

  • although there's a lot of interesting research into this right now too, so...

  • there are just a LOT of unknowns.

  • Problem two: You can only seed clouds that are already there

  • you can't make clouds appear out of thin air.

  • There has to be enough water vapor in the air already for cloud seeding to work,

  • so in extremely dry areas already devastated by drought,

  • this isn't much of a fix.

  • Three: We don't yet fully understand the implications of adding seeding chemicals to our water cycle.

  • Take silver iodide, for example.

  • Silver is toxic to many aquatic organisms in large doses, so we need to monitor the levels of these compounds

  • that may make their way into the water cycle.

  • And while dry ice, potassium chloride, and more can also be used for cloud seeding, depending on the situation,

  • the environmental effects of these will need to be considered too.

  • And four: Does cloud seeding upset the balance of nature even more than climate change-induced drought already has?

  • Some scientists worry that increasing the volume of clouds in one place will pull moisture from another area,

  • interrupting rain that could have fallen there insteadbut again.

  • The dynamics at play in clouds are so complex that it's really hard to say where rain would have fallen if we had left everything alone.

  • The fact remains that by 2030, almost half the world's population will live in highly water-stressed areas due to climate change.

  • And at least 52 countries all over the worldincluding the U.S., China, India, and Russia

  • have invested in weather modification technologies in the hope of bending the weather to their will.

  • So, while we investigate if and how cloud-seeding could help,

  • it's important to remember that it's really just a band-aid.

  • Experts say that if these strategies are seriously considered as a drought solution,

  • they must be part of a larger plan that involves smart water management.

  • And even if things like cloud-seeding will help, they treat a symptom, not the cause.

  • To ensure long-lasting solutions to droughts worldwide, change that will actually make a fundamental difference,

  • we have to address the root causes of the climate crisis too.

  • If this video left you thirsty for more info on clouds, check out this other video on cloud complexity here,

  • and let us know down in the comments what else you're interested in learning about weather modification.

  • Subscribe to Seeker to keep up with all your news on weather and climate, and as always, thanks for watching.

  • I'll see ya next time.

As devastating droughts threaten regions across the world,

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Could We Control the Weather to Solve Extreme Droughts?

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    Summer posted on 2021/06/28
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