Cloud seeding

 

I am unconvinced any of this is particularly useful except in local spots which may satisfy rubber neckers but is pretty meaningless when you need a broad drenching rainfall that breaks a drought over a mere thousand square miles.

That would likely demand a thousand planes loaded with enough material for spraying a thousand miles of flying.  Not a promising aspect.

Now we know why experiments around hurricanes were meaningless.

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Cloud seeding

 

It just might work

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It sounds like the stuff of cartoon supervillains, but weather modification techniques like cloud seeding could be a powerful tool as the planet warms and droughts worsen.

Seeding clouds aims to squeeze more precipitation out of them, boosting rainfall in dry areas and adding to the snowpack that feeds streams and rivers winding down from mountains. It’s a product of WWII-era scientific utopianism resurrected to head off climate-change-era dystopias, and it could be a last-ditch effort to halt global warming itself. Water managers from Australia to Israel to the American West are investing millions of dollars into the technique, with China—which has a considerable need for it—leading the way.

But like cartoon supervillains, we don’t know if our tech works. Despite its long history and the fairly basic principles behind it, proving the technology’s efficacy is a devilishly difficult science experiment. Let’s check the forecast.

By the digits

5%–15%: Amount of extra snowfall a 2014 study determined we could induce through cloud seeding, under the best conditions

120 mm: Maximum annual rainfall in the United Arab Emirates
$558,000: Amount the UAE spent on cloud seeding in 2015
56: Countries that cloud-seed
10: US states that cloud-seed
$17–$21: Cost per acre-foot of renting water, according to Idaho water manager Shaun Parkinson
$3.50: Estimated cost per acre-foot of generating water through cloud seeding
$168 million: Cost of a recent Chinese cloud-seeding experiment
100: Cloud-seeding machines in Colorado
$1 million: Annual cost of Colorado’s cloud-seeding program

1 million: Number of cloud droplets needed to make a raindrop

EXPLAIN IT LIKE I’M 5!

How do you seed a cloud?

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Cloud seeding is supposed to wring more precipitation out of a cloud using water vapor that’s already floating in the air, waiting to fall.

Some types of clouds are full of “supercool” water vapor—which means the droplets are colder than 0°C (32°F), but they haven’t frozen yet. Although your science teacher might have glossed over this, water doesn’t automatically freeze when it hits the freezing point. It takes some doing to get free-flowing liquid water molecules to arrange themselves into the orderly crystals that form ice. Once the water gets cold enough, it needs a seed to kick things off.

A seed can be almost anything—a fleck of ice, a dust particle, or even some species of bacteria. Cloud seeding generally uses silver iodide, which has a chemical structure that closely mimics an ice crystal. There are different methods for getting the seed into the clouds. You can shoot silver flares out of an airplane, or you can use ground based machines to float the particles into the air like incense.

Once the seed particles hit the cloud, the theory is that supercool water droplets will glom onto them, form ice, and then more droplets will attach onto that ice. Before long, they’ve formed snowflakes heavy enough to fall, and voila—extra precipitation hits the ground below.

☔️ The world’s supply of cheap and clean water will likely plummet as the climate warms and populations boom. Can we find ways to conserve, cut waste, and find new sources before it’s too late?