346 BULLETIN AMERICAN METEOROLOGICAL SOCIETY

NEWS AND NOTES

Air Force Scientists Develop Technique The feasibility of dissipating supercooled clouds by for Cutting Holes in "Cold" Clouds seeding with dry-ice was recognized many years ago. Airborne equipment, previously developed to do this, A new technique for creating holes in supercooled cloud crushed large blocks of dry-ice into particles suitable for layers has been developed by Air Force Cambridge Re- seeding purposes. search Laboratories scientists. During recent flight tests This equipment had two particular limitations. First, using this technique, holes more than 3 miles wide were these machines produced about half powdered dry-ice created in supercooled clouds. which evaporated immediately upon dispersal from the Major James F. Church, project scientist in AFCRL's aircraft and was wasted. Second, the logistical problem Meteorological Research Laboratory is directing research of supplying enough dry-ice where needed and the high on the dissipation of supercooled stratiform clouds. The evaporational losses suffered during storage until used, program is under the technical management of the Air severely limited the utility of this technique. Force System Command's Electronic Systems Division. The Cloudbuster makes ice pellets by passing liquid

The principal objective of this research is to provide C02 through an expansion nozzle and then compacting Air Force cargo and transport pilots with an economical the solid dry-ice powder, which is then formed, into proper capability to seed supercooled clouds with dry-ice pellets, size. The Cloudbuster has been designed with the capa- made on the aircraft and dispersed at will, to create bility of making different-sized pellets at the touch of a sizable holes in such cloud decks. lever, as well as varying the dispersal speed from two An entirely new machine has been developed which to 20 pounds per mile, while flying at 130 knots. will make dry-ice pellets as needed, directly from liquid Experimental tests were conducted this winter near carbon dioxide stored in the seeding aircraft. This Goose Bay, Newfoundland, from a C-130 aircraft which machine has been dubbed "The Cloudbuster"—because it was specifically instrumented for cloud physics research. does just that. Another series of field tests, next fall, is required to

This picture of the Cloudbuster shows the cyclone separator (top) which separates the dry-ice snow from Air Force Cambridge Research Laboratories scientists the gas phase formed during the initial expansion of the made this more than three-mile-wide hole in a super- liquid C02. The dry-ice snow drops out of the cyclone cooled cloud deck in one hour. Eleven pounds of C02 and is carried to the large pellet-forming wheel (shown pellets were used to create the opening. The objective to the right of the cyclone). A retractable chute is of the research that led to the development of this tech- inserted into the rectangular area to the right of the nique is to provide Air Force transport pilots with an pellet-forming wheel which dispenses the C02 pellets as well as vents the expanded gas overboard. In the lower economical capability to seed supercooled clouds with left foreground are the Cloudbuster controls which dry-ice pellets, made on the aircraft and dispersed at measure the rate of liquid C0? flow and pellet formation. will, to create sizeable holes in such cloud decks. VOL. 43, No. 7, JULY 1962 347 determine the best method of using this technique. The nology ; Sherman Lowell and Michael Yanowitch, Adelphi remaining tests will establish whether a single pellet size College; Herbert Riehl, Colorado State University; and and seeding rate will efficiently dissipate all types of Ralph Shapiro, Air Force Cambridge Research Labora- supercooled clouds and fog as well as serve all mission tories. requirements. The first of NCAR's programs to provide facilities There is an added flight safety factor available to to the scientific community is already under way. This aircraft equipped with the Cloudbuster system. The tank is the NCAR National Balloon Program, the purpose of of C02 can easily be connected to an aircraft's existing which is to spur rapid improvement in balloon tech- fire fighting system. This would virtually remove the nology; e.g., development of stronger and thinner balloon danger of an unextinguishable aircraft fire. films, of balloon systems capable of reaching heights Two contractor organizations contributed to the above 150,000 ft, and of reliable methods of launching progress of this program. Allied Research Associates, and recovering very heavy loads. To this end, NCAR Boston, Mass., designed and built the Cloudbuster ma- has acquired a year-round, 183-acre site at Palestine, chine. Technical Operations, Burlington, Mass., designed Texas, which provides improved climatological conditions the experimental cloud seeding flight experiments and for recovery of scientific payloads. Operation of the made the statistical summarization of the data collected $400,000 station will be under the NCAR Balloon Devel- thus far. opment Group, headed by Vincent E. Lally. Supercooled clouds, which form at below freezing Use of the site will be open to all scientists with balloon temperatures, occur with increasing frequency from the experiments on the basis of merit alone. For some upper-half of the United States northward to Alaska. studies, the Center will supply balloon flights, or flight The Cloudbuster technique will dissipate supercooled elements, for experiments funded from other sources and clouds, only. approved by the NCAR panel on scientific use of balloons, Another meteorological problem which is currently Verner E. Suomi, chairman. being investigated by AFCRL scientists is the formation NCAR will develop facilities only after a need has been and dissipation of warm fog and stratus clouds, which clearly established on the basis of studies of university develop in above freezing temperatures and are found in requirements for such facilities. Once the needs are all temperate and tropical regions. defined, the Center will take steps to see that they are met either directly by NCAR or by arrangement for their provision elsewhere. Current and Planned Studies at NCAR

Included in a report prepared for the National Academy of Sciences, IGY BULLETIN by Edwin L. Wolff, staff Special Seminars at MIT member, Office of the Director, National Center for A number of special seminars have been held during Atmospheric Research, are some notes on the current 1962 at the Massachusetts Institute of Technology. In work at the Center and its plans for the future. January, Dr. Friedrich E. Volz of the Blue Hill Me- Current scientific work at NCAR includes micro- teorological Observatory, Harvard University, lectured analysis of atmospheric particulates and chemical con- on "Twilight, Stratospheric Dust and Ozone." In stituents, by James P. Lodge and his staff; theoretical February, Dr. Frank H. Ludlam, Department of Meteor- studies of various aspects of the general circulation, by ology, Imperial College of Science and Technology, Philip D. Thompson and Aksel Wiin-Nielsen; and in- University of London, delivered an address on "Convec- vestigations in ionospheric physics and plasma physics, tive Cloud Structure." by Andrew Skumanich and Friedrich Meyer, who is at NCAR on a one-year visit from the Max Planck Institute On 23 March, Dr. Robert Jastrow, director of the for Physics and Astrophysics, Munich, Germany. Institute for Space Studies, began a series of five lectures Patrick Squires of Australia arrived in late February on "The Physics of the Earth's Atmosphere." The 1962 to begin organizing the Center's program in cloud individual lectures were entitled: Origin of Planetary physics. Later this year, Hans Dutsch and Jitendra Atmospheres, Energy Sources in the Middle and Upper Dave will join the NCAR staff and begin a program in Atmosphere (in two parts), The Ionosphere, and The radiation physics; Arnt Eliassen of the Institute of Magnetosphere. Theoretical Physics, University of Oslo, and Ragnar Dr. Robert G. Miller, Travelers Research Center, Inc., Fj^rtoft from the Norwegian Meteorological Institute Hartford, on 24 March conducted a special seminar on will spend sabbatical leaves at NCAR in pursuit of "Some Results of Multiple Discriminant Analysis in dynamical studies. Meteorology" in the afternoon, after having given a About a dozen visiting scientists are expected to spend morning lecture in the course "Statistical Problems in from one to three months at NCAR this summer. A Meteorology." His colleague, Isadore Enger, research similar program in 1961 brought the following summer associate in the Mathematics and Statistics Division, visitors to Boulder: Glenn Brier, U. S. Weather Bureau; Travelers Research Center, provided a special lecture Eric B. Kraus, Woods Hole Oceanographic Institution; in April on the use of contingency tables in weather Edward N, Lorenz, Massachusetts Institute of Tech- prediction and forecast evaluation.