How effective is Cloud Seeding?

Mick West

Administrator
Staff member
Cloud seeding has been done since before the 1950s , with the intent of increasing precipitation. But does it work? Research seems to indicate that yes it probably does, but only a little, and then only on average.

http://fivethirtyeight.com/features/we-may-never-know-how-well-cloud-seeding-works/

After nearly a decade of work, scientists concluded that cloud seeding could boost precipitation by 5 to 15 percent. The evidence came from an experiment in which two adjacent mountain ranges in southern Wyoming — the Medicine Bow and Sierra Madre — were randomly selected for seeding when conditions were amenable. Given the close proximity of the two ranges, they’re often hit by the same storms, so the unseeded range could serve as a control when the other was seeded. Researchers measured the results with snow gauges located in the target areas, as well as in areas outside the seeded zone for comparison. In addition, they analyzed snow samples to find out if the silver iodide was present in snow and whether it was accumulating in the environment in significant levels. (The answer to the latter question was no.) The researchers also used high-resolutionWeather Research and Forecasting modeling to simulate seeding operations.
...
It’s important to put the numbers in context, says Deshler, the University of Wyoming scientist. When he and a graduate student looked at climate data on these mountain ranges over the past eight years, they found that only about 30 percent of the precipitation that fell came from storms that had the right temperatures and wind directions to be seeded. If you assume that you can get a five to 15 percent bump in precipitation out of those storms, you’re now looking at a total increase of precipitation of only about 1.5 to 4.5 percent, he says. “Water managers need to be realistic about what the real benefit is. You can’t take that 15 percent and say that’s 15 percent more snow over the winter.”
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WeedWhacker

Senior Member
Cloud seeding has been done since before the 1950s...

indeed. Related info showing that the 'idea' goes back even earlier in time:

http://science.howstuffworks.com/nature/climate-weather/atmospheric/control-weather.htm

(Just one pertinent excerpt...the entire web page is worthy of reading, and understanding):


Numerous Native American tribes, especially those living in semiarid desert country, such as the Pueblo, Hopi and Zuni, engaged in elaborate dances to coax moisture from the rain-stingy skies. In the late 1800s and early 1900s, rainmakers roamed across the western United States, promising to end droughts for a fee.

These itinerant salesmen used a combination of pseudo-science and grand showmanship to convince communities that their technique, often a device or structure used to deliver chemicals or gases into the air, would bring rain in short order. Even the U.S. government got in on the act. In 1891, Congress appropriated $19,000 to conduct rainmaking tests in Texas under the guidance of Robert Dryenforth. Dryenforth's results were inconclusive, and as the century turned, politicians and citizens began to regard rainmakers with increasing skepticism.
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Of course the excerpt above involved attempts to make precipitation from only ground-based methods (before the invention of the airplane...although there were other "flying machines" prior to 1903! Hot air balloons, notably).

I fear that in modern "parlance" the word 'seed' conjures a wrong impression in some peoples' minds.....in that we can "plant seeds" in soil, and then "grow" something. Thus, the implication that it's possible to "plant something" in clear air, and "grow" clouds. (**)

(**) ...although, that is exactly how and more importantly, why contrails form.....but of course has nothing to do with "seeds" in that instance....only chemistry. [...]
 
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skephu

Senior Member.
Operation Popeye in the Vietnam war was apparently a success. Wikipedia writes: "The operation seeded clouds with both silver iodide and lead iodide, resulting in the targeted areas seeing an extension of the monsoon period an average of 30 to 45 days." That sounds impressive, although I didn't find a reliable source for this statement.
 

SR1419

Senior Member.
Operation Popeye in the Vietnam war was apparently a success. Wikipedia writes: "The operation seeded clouds with both silver iodide and lead iodide, resulting in the targeted areas seeing an extension of the monsoon period an average of 30 to 45 days." That sounds impressive, although I didn't find a reliable source for this statement.


That does sound impressive but I do not see how cloud seeding can extend/effect long range weather patterns when it is designed to simply enhance precipitation in the immediate sense in any given rainstorm.

Cloud seeding doesnt make clouds or storms it (maybe) provides incremental increases in rain already falling.
 

muttkat68

Member
That does sound impressive but I do not see how cloud seeding can extend/effect long range weather patterns when it is designed to simply enhance precipitation in the immediate sense in any given rainstorm.

Cloud seeding doesnt make clouds or storms it (maybe) provides incremental increases in rain already falling.

Cloud seeding was used as a weapon in Vietnam.

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WeedWhacker

Senior Member
Cloud seeding was used as a weapon in Vietnam.

Yes, it was....dubbed "Operation Orange": colloquially...seems it had another "code-name:...."Agent Orange".

TWO factors or 'elements' in that plan. ONE was defoliation, as explained below...another was the fact that in that region of the World it was possible to "seed" clouds in attempt to induce heavy precipitation....which would mean RAIN (not snow...too warm for snow). To induce an impediment to the so-called "enemy" (the North Vietnamese.) ...and to impede their ability to operate ground vehicles.

Back then? This was (now deemed illegal) an attempt to use defoliants and herbicides, to destroy jungle foliage, and thus remove the "cover" that the (then "enemy") used to evade detection.

In any event, notwithstanding the concept, and any sense of "whether or not it was Legal??" at that period of time....(or even if it was "ethical"??).

These sorts of 'sprays' were conducted at VERY low altitudes.

NOTHING at all to do with the more "modern" meme of so-called "chem"trails. (Although this is often brought up in the context of the so-called "chem"trail "debate", unfortunately, and inaccurately).
 

JDubyah

Member
Operation Popeye in the Vietnam war was apparently a success. Wikipedia writes: "The operation seeded clouds with both silver iodide and lead iodide, resulting in the targeted areas seeing an extension of the monsoon period an average of 30 to 45 days." That sounds impressive, although I didn't find a reliable source for this statement.

That's the difference with the experiment at the top of this post and the Popeye exercise: The experiment was just that, and experiment with a control area, and an experimental area. The Popeye exercise *seemed* to work, however there's no way of telling if that particular monsoon season would have been an exceptionally long one anyhow, if they hadn't seeded. That's what a lack of control does. It seems it worked compared to previous years, and against the average, but outliers do exist, and Popeye could have coincided with an outlier year. Or, it was an exceptional year made more exceptional by the 5-15% increase of cloud seeded.

I'm not saying that's the case.. I'm sure the military was far more gung-ho with the seeding than in the experiment that was part of this post, and that a monsoon is waaay more productive in terms of potential rainfall than the areas in the experiment. But it needs to be considered that Popeye was a military exercise, and not a controlled experiment at all.
 

deirdre

Senior Member.
Back then? This was (now deemed illegal) an attempt to use defoliants and herbicides, to destroy jungle foliage, and thus remove the "cover" that the (then "enemy") used to evade detection.

In any event, notwithstanding the concept, and any sense of "whether or not it was Legal??" at that period of time....(or even if it was "ethical"??).

These sorts of 'sprays' were conducted at VERY low altitudes.

NOTHING at all to do with the more "modern" meme of so-called "chem"trails. (Although this is often brought up in the context of the so-called "chem"trail "debate", unfortunately, and inaccurately).

Operation Orange/ Agent Orange had nothing to do with cloud seeding.

or am i wrong?
 

WeedWhacker

Senior Member
There was no such thing as "Operation Orange".

YOU are entirely correct.....I had multiple brain farts, and completely conflated the "Agent Orange" compound that was sprayed as a defoliant with the other program...mixing up the various programs' "names" and designations.
 

Mick West

Administrator
Staff member
The topic here is is cloud seeding is effective. Please try to avoid introducing other topics.
 

JDubyah

Member
AFAIK Operation Popeye was conducted over several years, not just a single year.

Yes, it was 1967-1972. I should have said 'period' rather than a particular year. They talk about how it extended the monsoon season by an average of 30-45 days, but I don't know the year-by-year breakdown of the season length that compose that average.
 

Belfrey

Senior Member.
Some articles about Operation Popeye indicate that evaluations of its effects were inconclusive, and that the extensions of the monsoon season were due to tropical storms, not cloud seeding. See here for one example of a well-written article that unfortunately does not cite sources. Apparently there were analyses done, but I can't find primary sources on the topic.
In the end, however, it proved impossible to determine the amount of additional rainfall caused by cloud-seeding rather than other factors, and thus justify the recurring outlay. The Defense Intelligence Agency estimated that seeding increased rainfall "in limited areas up to 30 percent above that predicted for the existing conditions," but this figure admittedly was the result of "empirical and theoretical techniques based on units expended and the physical properties of the air mass seeded"-in short, a scientific guess. Sensor data showed only that the enemy consistently experienced difficulty keeping traffic moving through the monsoon rains, a normal problem for that time of year.

From time to time, especially during 1971, tropical storms either intensified the downpour associated with the southwest monsoon or extended the rainy season beyond its anticipated close. Atmospheric conditions over either the Indian Ocean or the South China Sea, rather than cloud seeding over southern Laos, spawned these typhoons. Ironically, typhoon-induced rains interfered with cloud seeding, cooling the earth and preventing the updrafts of heated air that were essential to the project.
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SR1419

Senior Member.
Here is a recent article in the San Francisco paper about current cloud seeding efforts right over Mick's head :)

http://www.sfchronicle.com/bayarea/...2.php?google_editors_picks=true#photo-9728254

“We’ve had quite a few seeding opportunities up here this year,” said Ken Ericsson, senior meteorologist for PG&E, noting that storms during this year’s El Niño enabled them to seed, increasing snowpack an estimated 6 percent.
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Fray Crease, water agency manager for Santa Barbara County, said the criticism she hears most about her county’s cloud-seeding program is that it’s part of the purported “chemtrail” agenda.


The conspiratorial fear is that the planes used to enhance precipitation are actually among a larger government fleet of aircraft that disperse subversive chemicals for dark purposes onto an unsuspecting population.
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Marin B

Active Member
For those like me who have little knowledge of cloud seeding, I found this FAQ publication by the Tasmania government informative. They say cloud seeding can increase rainfall by at least 5%. Seems like such a small percentage - how can they really say with certainty when they're dealing with something so variable as rainfall amounts? I was curious about how much silver iodide is used. The publication says < 1/2 tsp per square kilometer, which doesn't seem like much.

ETA: I looked at the original post, which pretty much answers the question I asked.
 

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