How Cloud Seeding Can Draw bigger Rain and Snowfall

Here in Modesto, California,pilots are prepping this plane to fly into thecenter of a storm. Flares on the wings andfuselage will inject a substance called silveriodide into the storm clouds, causing waterwithin the clouds to freeze and increasing the amountof precipitation that falls. We can't make a storm happenand we can't create conditions in this stormthat are ideal. Those happen naturally. Andwhat we're doing is just.

Taking advantage ofexisting conditions, naturally occurringconditions, and trying to make the storm again moreefficient from a water supply perspective. It's called cloud seeding,and as futuristic as it sounds, it's been aroundsince the 1940s. Today, states, utilitycompanies, and ski resorts alike pay companies likeWeather Modification International significantmoney to seed storm clouds.

And increase snowfall inthe drought-ridden American West and worldwide. The current project is about$4 million a year. We're very well supported. We have a lot of localstakeholders that are investing in it. Until recently, the evidencefor cloud seeding's efficacy was murky. But research hasfinally shown unequivocally that it works, and there'sbeen no evidence to show.

That the seeding agent,silver iodide, is harmful at the current level that it'sused. Blestrud says that Idaho Power sees an 11% or12% increase in snowpack in some areas that it seeds,while Carkeet says Turlock's program results in about60,000 to 90,000 extra acre-feet of water everyyear. While it's no cure for theWest's historic drought, dozens of cloud seedingprograms across the country are ramping up right now aswinter gets underway.

These are the flares that wewill use when we're above cloud, and we need to getthe flare down into the cloud. When we're in cloud,we will be using the burn-in-place flare, whichcan be ignited from the cockpit one at a time. They burn for four to fourand a half minutes and they just trail smoke out withthe silver iodide. The world's first cloudseeding experiment back in 1946 was a bit moresimplistic than Zimmer's.

Current setup. There was a group ofscientists back in New York that worked for the GeneralElectric Company. They released some dry iceinto the top of a super-cooled stratus cloudand caused ice to form, and that ice formed and used upthe available liquid water of the cloud drops andcloud seeding was thus born. Supercooled means liquidthat is below its freezing point, but hasn't yetcrystallized. Injecting.

Silver iodide into cloudsthat contain supercooled liquid water causesdroplets to freeze together and form snowflakes, whichfall to the ground when they reach a certain size.Absent the freezing process, these supercooled dropletswouldn't become heavy enough to precipitate as eitherrain or snow. The cloud initially is allwater. Eventually, as it getstoward the summit of the mountain, it may be 50% iceor maybe more than that.

Even if it is, there'sstill a lot of liquid water left there. And theprecipitation that's forming has a very short time toget big enough to fall out before it crests themountain and starts to descend and thus warm. And so that's the window ofopportunity. For cloud seeding pilots,this is when they fly into the storm, which is no easytask. The first thing we do forsafety is turn on all the.

Aircraft ice protectionsystems. Weather radar is importantfor us so we don't get into a convective environmentlike an embedded thunderstorm or somethinglike that. An average flight lastsbetween two and four hours. By the time the wheels areup, you're in cloud and we're in cloud the entiremission until we're shooting an approach back into anairport and then pop out of the clouds and have avisual on the runway.

Yeah, it feels like you'rea subcommander in the Navy. You don't see anything. Zimmer seeds clouds for theTurlock Irrigation District in Northern California fromNovember through April every year. We do a preflight check andtake off and head to our seeding area, which is overthe Sierra Nevada mountains. If we are flying in cloudwith decent supercooled liquid water, the mosteffective tool we have is.

The burn-in-place flare onthe back of the wing, because it's going directlyinto the cloud and mixing with that supercooledliquid water. If we're just above cloudor at cloud top and we're a little bit colder thanwhere we want to be with the burn-in-place flares, wecan transition to the injectable flares whichshoot the silver iodide down through a warmer layerbelow us to find that minus five degrees Celsius levelwhere they're most effective.

In forming ice. From a water supplyperspective, it's most valuable to seed cloudsover mountains where the water is stored as snowuntil the spring runoff. If you put it in themountains, the drainages coming out of the mountainsoften have reservoirs on them, and so you cancapture it that way. When it's out on theplains, such as North Dakota, it's still abenefit because it helps.

Recharge soil moisture, butit can't be stored and used for a later date. Texas, for example, usescloud seeding to help irrigate fields forfarmers, while st ates like Idaho, California,Colorado, Utah, and Wyoming use it to help fill uptheir rivers and reservoirs. Most use planes to do cloudseeding, but some programs use ground-based flares. There are multipleutilities, both south of us.

And north of us that havecloud seeding programs. It's a lot more common thanpeople think. More basins have a seedingprogram than do not have a seeding program. For much of cloud seeding'shistory, its success was measured by comparing thesnowfall in an area where cloud seeding occurred to anearby control area. And then you look aftercloud seeding happens and if there's a shift in that soyou get more than what's.

Expected in the targetarea, then you can equate that to cloud seeding. This method convinced manystates and utility companies like Idaho Power of cloudseeding's efficacy long before tech was good enoughto actually see the changes taking place within theclouds themselves. However, there were stillplenty of skeptics, given how hard it was to verifycause and effect due to the many variables at play in astorm.

But a 2017 collaborativestudy between various universities, Idaho PowerCompany, and the National Center for AtmosphericResearch, called SNOWIE, gave researchers a clearvisual of what happens as a cloud seeding plane zigzagsthrough a storm. So you could actually seethat cloud turn from what's called a supercooled liquidwater cloud, a cloud that has a bunch of water that'sbelow freezing but stays in the liquid state, and thenit started to turn to ice.

And it started to grow to asnowflake. And the radar can then seethose snowflakes on it and they could start to seethat zigzag pattern there. The ultimate impact of cloudseeding varies according to location and the nature ofthe storm, though studies show an overall 5% to 15%increase in precipitation can be expected. A smallpercentage of that total will be absorbed into thesoil, while the rest will become runoff that'shopefully stored in one of.

The West's shrinkingreservoirs. The Turlock Irrigation District has amax budget of $475,000 per year for its cloud seedingprogram, and says it's seen a 3% to 5% increase inrunoff since it started seeding in 1990. It's percentage wise andit's within the realm of natural variability. It's one of the things thatmakes it so hard to evaluate is you don't see a doublingor tripling of the.

Precipitation. You see anincremental increase, but you add that up over thecourse of a winter and then it can be significant. And cost-wise, Boe says thatit's almost always worth it. It's kind of, well, I won'tsay a no-brainer, but it makes a lot of sense towater managers to go ahead and do it even if theincrease is on the order of a few percentage points. It's still cost effectiveto do it.

When you run the numbers,Blestrud says the multimillion dollar cloudseeding program that Idaho Power oversees yieldsbillions of gallons of additional water at a costof about $3.50 per acre-foot. That's comparedto about $20 per acre-foot for other methods ofaccessing water, such as through a water supplybank. States in the lower ColoradoRiver Basin like California, Nevada, and Arizona areeven helping fund.

Out-of-state cloud seedingoperations in the upper basin states like Utah,Wyoming, and Colorado, hoping excess water willmake its way into their lower basin reservoirs. States are putting moneyinto those programs, knowing that they have no legalclaim to any of that water. But since the localsalready have enough water, they're figuring theadditional water is likely going to pass down into theGreen and into the Colorado.

And make it down their way.So to them, it's very worthwhile to do it. While cloud seeding is mostcommonly used to increase precipitation for droughtalleviation, it can also be used to suppress hail andclear fog around airports. Internationally, there'sbeen concern that cloud seeding has led toincreased flooding, such as in the UAE. This remainsunproven, though some experts are pushing for aninternational body to.

Regulate weathermodification activities. So far this year, theTurlock Irrigation District has conducted six cloudseeding missions. We're flying below averageright now. We're hoping we get thatatmospheric river to show up and bring bring moremoisture to California. Now that studies havevalidated the efficacy of cloud seeding and as thedrought in the West persists, interest in thisdecades old tech is peaking.

Both nationally andglobally. We're busy right now. Wehave new contracts starting in the Middle East. Weoperate in India, Canada, Wyoming, Idaho, California. Right now, we have deployedevery aircraft that we have access to that we, thecompany, owns. We don't have anythingsitting in reserve. But as seeding operationsramp up for the winter, Boe warns that this tech canonly go so far when it comes.

To alleviating our waterwoes. For us, it's reallyimportant that people that want to engage in cloudseeding technology do so with the perspective ofwater management, not solution to a drought. Because when you're in thethroes of a big drought, you're going to have farless opportunities to actually seed clouds. So you need to view itlong-term as a water.

Management tool, not as aknee jerk reaction because you're in a drought.

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