Cloud seeding
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Comment by Matthew Bamberg on December 31st, 2011 at 10:09 am
You’re missing FACE (Florida Area Cloud Experiment) project, which was conducted by NOAA for many years during the 1970s. I worked in that program. Dr. William Woodly directed it.
Comment by James M Schaefer, Ph.D. on March 24th, 2012 at 7:31 am
There is much to learn from the actual serendipitous discovery as described in my father’s forthcoming autobiography “Serendipity in Science.” I am pasting part of a chapter that could be edited into the article under the History section. Bernie Vonnegut was a colleague and close friend of Dad’s, in fact Dad hired Bernie to work at the Atmospheric Sciences Research Center at SUNY Albany from the 1960s throughout their lives.
Pasted: “During the spring of 1946 using a 6 cubic foot G.E. Cold Chamber I made a concerted effort to modify a supercooled cloud. I found that the temperature of the chamber varied from -10°C at the top to -20°C at the bottom and 15°C near the middle.
“I dusted into the chamber dozens of materials ranging from chemical dusts to natural soils. While some of these formed a few glinting ice crystals none of them showed any encouraging effects.
I found the cold chamber to be an ideal testing device. Lined with black velvet and illuminated with a concentrated filament lamp that cast a shaft of bright light at a 45° angle across the length of the chamber. A single ice crystal could readily be detected in the super cooled cloud in the chamber. Exhaling ones breath into the chamber directing it toward the bottom could easily produce such a cloud. The temperature inversion in the chamber was so intense that the turbulence generated by the moist breath would die out in less than 10 seconds. I found it important in supplying moisture with the breath, to exhale rather than blow. The latter entrains warm, drier air from the air surrounding the top of the chamber and thus tends to warm the supercooled cloud.
Irving Langmuir (top left), Bernard Vonnegut( top right) and Vince Schaefer. On July 12, 1946 Vince Schaefer discovered cloud seeding. Photo courtesy Schenectady Museum.
By early July I had reached an impasse in my experiments and was trying to figure what to do next. Then suddenly a serendipitous event occurred. The morning of July 12 was humid and quite warm. Checking the temperature of the cold chamber I found it to be warmer than usual. To cool it down I got a large chunk of dry ice from our storage bin to overcome the warmth of the chamber. The instant the dry ice was lowered into the chamber I saw to my delight that the supercooled cloud had been displaced by a strange bluish fog unlike anything heretofore seen. Quickly lifting the dry ice from the chamber I introduced moisture from my breath and gradually decreased the density of the fine particle blue fog until I could see the glinting of the incredible numbers of ice crystals. After spending five minutes or more growing these crystals I finally was able to produce a supercooled fog.
I then put a smaller piece of dry ice in the chamber only to see it again revert to a bluish fog. Repeating my procedure to cause the fallout of the ice crystals I then held the chunk of dry ice above the chamber, scratched its surface with a nail and saw a magnificent cluster of condensation trails appear in the supercooled cloud through which the tiny grains of dry ice had fallen. Once I had this incredible phenomenon under control I summoned all of my “neighbors†to see the spectacular display. Unfortunately the Boss was on the west coast on a lecture tour and it was nearly a week before he returned to see it. Needless to say he was very excited when I showed it to him, and he summoned a number of his friends to see it.
He told me I should make plans to conduct some experiments with atmospheric clouds and I soon arranged for the cooperation of the G.E. Flight Test Center at the Schenectady County Airport. The Director of the Center, Mr. Curtis Talbot, volunteered to take me up in his Fairchild Cabin plane, so I designed and built a motor driven CO2 dispenser which I planned to use for dispensing crushed dry ice as the plane flew over or through the atmospheric cloud.
On November 14, 1946 Vince Schaefer creates manmade snow for the first time. Photo courtesy Schenectady Museum.
As tends to happen with most atmospheric experiments the fall of 1946 was a period of clear skies! Day after day in October and early November I would get up early, look at the sky and feel disappointed. This continued until the morning of November 13 when a series of parallel bands of clouds were in the sky over our area which appeared large enough to be seedable and high enough to be supercooled. I called Curt Talbot and then headed for the local dairy to obtain the dry ice needed, alerted Langmuir and was able to take off from the Schenectady Airport at 0930.“
Comment by James M Schaefer, Ph.D. on March 24th, 2012 at 7:36 am
You are missing a great amount of detail about the discovery process by Vincent J Schaefer (1906-1993). His autobiography “Serendipity in Science” will soon be released (2012) — Also see him narrate the discovery process on Youtube — Vincent Schaefer-Snow.
Comment by Jennifer Tanabe on April 23rd, 2012 at 5:12 pm
Thank you, Matthew, for your feedback noting that the Florida Area Cumulus Experiment (FACE) was missing from the history. That project has now been included.
Comment by Jennifer Tanabe on May 21st, 2013 at 2:45 pm
Thank you, Dr. Schaefer, for your feedback. Your father’s autobiography has been added to the references section and the history section has been expanded.
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