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Sue Ellen Haupt, Robert M. Rauber, Bruce Carmichael, Jason C. Knievel, and James L. Cogan

weather modification has progressed hand in hand with scientific understanding. The following two sections deal with two applications that are implicit parts of twentieth- and twenty-first-century progress and that could not function without meteorological knowledge—aviation ( section 3 ) and national security ( section 4 ). To limit the scope, both of these sections focus on advances in the United States, which did lead the world in these arenas for some time; more recently, however, parallel

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J. Michael Fritsch

Abstract

Modification of mesoscale convective weather systems through ice-phase seeding is briefly reviewed. a simple mathematical framework for estimating the likely mesoscale response to convective cloud modification is presented, and previous mesoscale modification hypotheses are discussed in the context of this mathematical framework. Some basic differences between cloud-scale and mesoscale modification hypotheses are also discussed. Numerical model experiments to test the mesoscale sensitivity of convective weather systems are reviewed, and several focal points for identifying mesoscale modification potential are presented.

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Sonia M. Kreidenweis, Markus Petters, and Ulrike Lohmann

recent time history of the number of papers on CCN and INP. Starting in the late 1950s there was significant interest in ice nucleation research, in part due to the hope of successful weather modification by cloud seeding. At the same time there was less interest in the nature of CCN. Twomey (1977) was a landmark article linking pollution, CCN, and planetary albedo, which is now referred to as the Twomey effect, an indirect aerosol effect (or radiative forcing) on climate due to aerosol

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Roscoe R. Braham, Jr.

Abstract

Schaefer's 1946 cloud seeding experiment initiated a quest for weather modification techniques. Progress has been slow; but there are several reasons for believing that useful precipitation augmentation may be possible.

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Robert D. Elliott

Abstract

This review provides a sketchy background of orographic weather modification activities prior to the 1960s, followed by a more critical review of major orographic projects carried out and reported in the scientific literature during the past 25 years. In the earlier of these major projects, evaluation of results had been based largely upon comparisons of seeded and nonseeded precipitation experimental units stratified by various sounding-derived parameters in an attempt to amplify the physical significance of the seeding effects within various sub-types of orographic clouds.

The later major projects are still underway with no final evaluations having been presented. However, a wealth of significant data analyses have been reported that provide important insights into the various natural and seeding precipitation mechanisms. Much of this is attributable to the new observational tools in use, which include airborne and ground microphysical sensors, doppler radar, and microwave radiometers.

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Sue Ellen Haupt, Steven Hanna, Mark Askelson, Marshall Shepherd, Mariana A. Fragomeni, Neil Debbage, and Bradford Johnson

1. Introduction Many of the advances in science in the past 100 years were spurred by an inherent human need to better understand the world in which we live. To that end, we have developed mental models, translated them into mathematical models, and, in the past century, built numerical models that can be implemented on modern computers. Correspondingly, the science of meteorology has advanced. Our ability to model the weather, environment, and climate has grown immensely, as documented in the

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Stanley G. Benjamin, John M. Brown, Gilbert Brunet, Peter Lynch, Kazuo Saito, and Thomas W. Schlatter

sample of line-printer output, enhanced manually, of a real-time 24-h forecast from the JNWPU and verification 1000-hPa heights for a case from May of 1956. No diabatic or viscid processes were addressed in these initial models. Table 13-3. The U.S. global operational models for the National Weather Service/Weather Bureau—major implementations (a detailed history of recent modifications can be found here: http://www.emc.ncep.noaa.gov/gmb/STATS/html/model_changes.html ). Here, NH indicates the

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Keith L. Seitter, Jinny Nathans, and Sophie Mankins

international policy related to the atmosphere from its earliest years onward, on issues from weather modification and the free and open exchange of data to effective relations between government weather services and the private sector. As the science matured, AMS was instrumental in working toward the use of research results in creating policy on issues influenced by weather and climate by publishing observations of weather impacts from above-ground nuclear testing ( Holzman and Cumberledge 1946 ) and

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Sue Ellen Haupt, Branko Kosović, Scott W. McIntosh, Fei Chen, Kathleen Miller, Marshall Shepherd, Marcus Williams, and Sheldon Drobot

insights through clustering and nonlinear analysis. This section looks to the future, but it also reverts to the past when science relied more on finding patterns in nature. Concluding thoughts and consideration of some prospects for the future appear in section 6 . This chapter is the final one of a three-part series on applied meteorology. In the first chapter, we considered some of the most basic and first-addressed application areas: weather modification, aviation applications, and security

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Jeffrey L. Stith, Darrel Baumgardner, Julie Haggerty, R. Michael Hardesty, Wen-Chau Lee, Donald Lenschow, Peter Pilewskie, Paul L. Smith, Matthias Steiner, and Holger Vömel

). Already recognized were the characteristic features of thunderstorms, squall lines, and frontal and hurricane echoes, and the limitations caused by attenuation of microwaves of wavelengths shorter than 10 cm were appreciated. The Weather Bureau (forerunner of the National Weather Service) had received airborne radars from the U.S. Navy in 1942 for modification and use as ground weather observing systems. A hybrid radar network in Panama was providing weather surveillance in 1944; in addition to

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