Fog Modification with Giant Hygroscopic Nuclei

Jiusto, James E.; Pilié, R. J.; Kocmond, W. C.

doi:10.1175/1520-0450(1968)007<0860:fmwghn>2.0.co;2

Cited by 17 publications

(7 citation statements)

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“…The work by HOUGHTON and RADFORD (1938) was the first to use hygroscopic particle seeding to dissipate fog droplets. JIUSTO et al (1968) studied the possibility of fog dissipation by giant hygroscopic nuclei seeding and stated that the use of carefully controlled sizes and amounts of hygroscopic (NaCl) nuclei can produce significant improvements in visibility. KORNFELD and SILVERMAN (1970) and WEINSTEIN and SILVERMAN (1973) also indicated similar results and stated that if the fog droplet size distribution is known, the seeding nuclei are to be chosen carefully for dissipating the fog.…”

Section: Introductionmentioning

confidence: 99%

Fog Research: A Review of Past Achievements and Future Perspectives

Gültepe

Tardif

Michaelides³

et al. 2007

Pure appl. geophys.

563

348

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The scientific community that includes meteorologists, physical scientists, engineers, medical doctors, biologists, and environmentalists has shown interest in a better understanding of fog for years because of its effects on, directly or indirectly, the daily life of human beings. The total economic losses associated with the impact of the presence of fog on aviation, marine and land transportation can be comparable to those of tornadoes or, in some cases, winter storms and hurricanes. The number of articles including the word ''fog'' in Journals of American Meteorological Society alone was found to be about 4700, indicating that there is substantial interest in this subject. In spite of this extensive body of work, our ability to accurately forecast/nowcast fog remains limited due to our incomplete understanding of the fog processes over various time and space scales. Fog processes involve droplet microphysics, aerosol chemistry, radiation, turbulence, large/small-scale dynamics, and surface conditions (e.g., partaining to the presence of ice, snow, liquid, plants, and various types of soil). This review paper summarizes past achievements related to the understanding of fog formation, development and decay, and in this respect, the analysis of observations and the development of forecasting models and remote sensing methods are discussed in detail. Finally, future perspectives for fog-related research are highlighted.

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Section: Introductionmentioning

confidence: 99%

Fog Research: A Review of Past Achievements and Future Perspectives

Gültepe

Tardif

Michaelides³

et al. 2007

Pure appl. geophys.

563

348

View full text Add to dashboard Cite

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“…In contrast, the haze droplets contribute 16-17 per cent to the visibility in the inland fogs at Visalia and 23 per cent in the coastal fog at San Diego . [14] or [15]) have shown that visibility in warm fog should be significantly improved by injecting a carefully chosen amount of giant hygroscopic nuclei of a particular size . In these investigations, however, the presence of the submicron haze droplets which coexist with the supermicron fog droplets was not considered .…”

Section: Haze Droplets and Visibilitymentioning

confidence: 99%

Calculated Effects of Haze Droplets on Visibility in Natural and Treated Warm Fogs

Hindman

Heimdahl

1979

Optica Acta: International Journal of Optics

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“…As discussed by Kocmond et al (1970), .reproducible fogs can be created and maintained inside the chamber. Jiusto et al (1968) investigated the physical characteristics of fogs produced within the chamber and found them to be very similar to typical inland radiation fog in terms of droplet radius, droplet radius range, liquid water content,. droplet concentration, and visibility.…”

Section: Seeding Effectivenessmentioning

confidence: 99%

Optimization of Warm-Cloud Seeding Agents by Microencapsulation Techniques¹

Nelson¹,

Silverman²

1972

Mon. Wea. Rev.

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Microencapsulation technology, whereby single crystals or solution droplets are chemically "packaged" inside thin coating shells, provides a method of optimizing the chemical and physical properties of warm-cloud seeding agents. Ethylcellulose-encapsulated urea and sodium chloride particles have been produced in the lsboratory and their hygroscopic properties investigated gravimetrically, microscopically in a diffusion chamber, and optically in a large fog chamber. These investigations indicate that microencapsulation provides for a relatively narrow particle spectrum with a sharp lower size limit, gives the particles more structural integrity, prevents degeneration of the particle spectrum and formation of "fines" during handling and dispersal, and greatly reduces clumping and caking during storage, handling, and dissemination. Hygroscopic properties of the seeding particles are not affected by the presence of the encapsulating coating. As an encapsulated particle grows by vapor diffusion in a humid environment, its core material is released by diffusion through its permeable but insoluble ethylcellulose shell. Individual seeding particles are thus unmistakably "tagged," providing an objective method for evaluating the seeding effects. The process lends itself to large-scale production and promises to be more ecosomical than mechanical milling and sizing to an equivalent size spectrum. 1 This research was supported by the Laboratory Directors Fund of the Air Force Cambridge Research Laboratorles. on the microphysical and chemical properties and, thus, on the warm-cloud seeding potential of hygroscopic materials, are discussed in this paper. The optimization of urea and sodium chloride, in particular, as warm cloud seeding agents is described. 2. MICROENCAPSULATION TECHNOLOGY Microencapsulation may be defined as a special technique of chemical packaging whereby very small crystals, particulates, or solution droplets are encased in thin coating shells. Possible encapsulation methods include organic phase separation, aqueous coacervation, meltable dispersion, and interfacial polymerization. Potential wall materials include nearly all waxes, and polymers possessing sharp melting points. By proper choice of capsular wall material, wall thickness, and morphology, microencapsulation can be used to alter significantly the chemical and physical properties of the encapsulated substance. Microencapsulation techniques are widely used in foodstuffs, pharmacology, and chemical engineering. A well-known example is the "tiny time pills" advertised by several commerical cold-remedies that employ microencapsulation to effect a controlled, sustained release of the pharmaceutical contents. A detailed review of microencapsulation techniques, effects, and usages is given by Herbig (1967). All microencapsulations discussed in this paper use ethylcellulose 'as the wall material, deposited on urea and sodium chloride particles by the process of organic phase separation.2 They are intended to serve as examples only. Other wall materials,...

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Fog Modification with Giant Hygroscopic Nuclei

Cited by 17 publications

References 0 publications

Fog Research: A Review of Past Achievements and Future Perspectives

Fog Research: A Review of Past Achievements and Future Perspectives

Calculated Effects of Haze Droplets on Visibility in Natural and Treated Warm Fogs

Optimization of Warm-Cloud Seeding Agents by Microencapsulation Techniques¹

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Fog Modification with Giant Hygroscopic Nuclei

Cited by 17 publications

References 0 publications

Fog Research: A Review of Past Achievements and Future Perspectives

Fog Research: A Review of Past Achievements and Future Perspectives

Calculated Effects of Haze Droplets on Visibility in Natural and Treated Warm Fogs

Optimization of Warm-Cloud Seeding Agents by Microencapsulation Techniques1

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Optimization of Warm-Cloud Seeding Agents by Microencapsulation Techniques¹