06/05/2008
Rainmaking
Following up on our space topics of last week, the Space Shuttle Discovery did deliver the billion dollar Japanese module to the International Space Station. More good news – the replacement Russian pump was installed yesterday at 11:27 AM EDT and, to quote a NASA mission update: “After a series of three tests, the replacement pump appears to be working. Mission Control Moscow has given the station crew a “go” to resume normal operations of the toilet system.” Meanwhile, on Mars, Phoenix has made at least two initial scoops of Martian soil, revealing at the bottom of one of the scoops a whitish colored material. The question is whether this whitish material is a salt or the surface of a layer of water ice. Stay tuned.
Down here on Earth, I’ve had my own plumbing problems. After a replacement of the innards of my toilet, everything works fine. Yesterday, however, we had new dishwasher delivered and our plumber and his son, also a plumber, worked for nearly three hours on our nearly 70-year-old house’s plumbing system to achieve delivery of water to the appliance. Unfortunately, I had chosen to replace our old dishwasher with one of more advanced technology, not knowing that its configuration was incompatible with the old water input system. The net result was that the plumbing cost more than the dishwasher!
To recover from the shock, I went out to gaze at the spectacularly lush and gorgeous rhododendrons in full bloom. This has been an unusually good year for flowering shrubs and trees in our region of New Jersey. I remember many years ago being in New Zealand and standing with my wife in a park absolutely in awe of the size of one rhododendron in full bloom. We were told that New Zealand’s volcanic soil and its climate provides superb conditions for growth of large specimens of many plants. Now, here in our own neighborhood, many rhododendrons have grown to the size that so impressed us in New Zealand.
Can it be that with global warming our climate is changing and becoming more like that in New Zealand? It has seemed to be an unusual spring with lots of rainy days but at the same time the total amount of rain has not been unusually high; maybe even lower than normal. Or is it just that weather seldom seems truly “normal”, especially if it rains more than it should on those days I’d planned to go golfing? Of course, I can’t complain about a washed out round of golf when compared to the death and suffering from monster cyclones and tornadoes in faraway countries such as Myanmar and here in the U.S.A. One can’t help wondering whether predictions of violent weather due to global warming are starting to come true.
If so, can we hope to, if not control the weather, at least take some of the sting out of hurricanes and other violent weather events? I remember some fifty or sixty years ago hearing about work along these lines at the General Electric Laboratory in Schenectady, New York. What prompted my recollection was an article by Donovan Webster titled “Reining in the Weather” in the June issue of Discover magazine. In the article Webster describes the work at GE of Bernard Vonnegut, brother of famed novelist Kurt Vonnegut. Bernard, in November and December of 1946, sent up a plane to release dry ice into clouds around Schenectady in an effort to seed ice crystals that would lead to precipitation. Whether coincidence or not, the biggest snowfall of the year accompanied the dry ice seeding.
I was troubled by the article and Vonnegut. He was not the person I remembered as being the one involved in weather modification but I suffered from the senior memory deficit and finally was forced to a search of the Internet to find the answer. The person was Irving Langmuir, a physical chemist whose work on surface science brought him a Nobel Prize in 1932. I may be wrong but I believe I heard him speak either at Bell Labs or at some meeting. I found a history of Langmuir’s work on the Web site of the New Mexico Institute of Mining and Technology; its Langmuir Laboratory for Atmospheric Research is devoted to the study of cloud processes leading to lightning and rain.
Langmuir was involved in the study of icing of aircraft in the 1940s, along with a member of his group, Vincent Schaefer, who had joined GE as a machinist. He and Langmuir, wanting to study how water freezes in clouds, went to Mt. Washington, known for its at times horrific weather, to carry out their studies. (I once rode the cog railway up to Mt. Washington in August shortly after a storm that had driven snow onto telephone poles so forcefully that clumps of snow more than a foot in length were extending horizontally from the poles.) Understandably, Schaefer didn’t enjoy the weather on the mountain, and came back to GE to devise a “cold box” in which he managed to simulate cloud formation. He then found, in July 1946, that if he introduced dry ice into the fog in his cold box an abundance of ice crystal formed. 1946 was to become a significant year in weather modification.
On November 13 of that year, Schaefer and a pilot found a cloud over the Adirondacks and from the top seeded it with dry ice particles. Snow began falling from the cloud’s base and cloud seeding was born. Earlier that year, Langmuir brought Bernard Vonnegut into the group. Vonnegut had also done work on icing and on freezing in solutions. He decided that it would be better to find some chemical compound that would nucleate ice crystals in clouds and finally came up with the compound silver iodide. Silver iodide’s crystal structure was sufficiently close to that of ice that, indeed, on November 14, Vonnegut introduced silver iodide particles into Schaefer’s cold box and got ice crystals to form. Then, as mentioned in Webster’s article, over a period of four days in November and December, Vonnegut sent up a plane to seed clouds with silver iodide.
The history of Langmuir and his colleagues from that point on is fascinating and controversial. They went to New Mexico, where storms and cloud formation was ideal for their work. There were attempts to modify rainfall in that desert area, as well as attempts to tame a hurricane. The latter may or may not have led to a change in course toward Savannah, Georgia and the seeding was described as a “low Yankee trick”. GE’s lawyer’s were becoming concerned about the seeding experiments leading to lawsuits and Langmuir was encouraged to stop. Seeding went out of favor and any efforts were low key.
Langmuir died in 1957 and seeding still goes on. Today, for example, Salt Lake City in Utah depends on weather modification to keep its airport open, according to the Discover article. It seems that from October to March there are frequent fogs that would close the airport. The fog forms when a front of warmer air sweeps in over colder air in the Salt Lake Valley between the Wasatch and Oquirth mountains. When this occurs or is about to occur, the call goes out to a company known as Barken Fog Ops. Up goes the company plane and several boxes of dry ice particles, which are dumped on top of the fog bank. Very soon after the dumping, ice crystals begin forming and a hole opens up in the fog. Sometimes the seeding is so successful that a snowstorm of a few hours duration occurs. Even with the snowstorms, the program is so successful that the airport saves tens or even hundreds of thousands of dollars that would be lost for each plane that would have been unable to land or take off in the fog. About 450 planes a day arrive at the airport.
Another successful program, seeding with silver iodide, to prevent or minimize hail damage to crops has been going on in North Dakota for over three decades. The silver iodide seeding may not prevent the hail entirely but does tend to make the hailstones smaller, lessening the damage. Crop insurance company statistics comparing seeded and nonseeded areas showed a 45 percent fewer number of hail damage claims in the seeded areas.
There’s much more that could be said about seeding and weather modification but for now I’ll be content if it doesn’t rain on Tuesday, my golfing day.
Allen F. Bortrum
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