摘要:

The study of neutrons in the solar system is reviewed, and the theories and experiments that relate to this study are described. Neutron capture in the atmosphere produces among other isotopes carbon 14 and tritium. The earth's neutron albedo is also a source of Van Allen radiation. The importance of the source is, however, in doubt; therefore, some studies of geomagnetically trapped charged radiation are also reviewed to emphasize the areas of greatest uncertainty in the theory of injection by the neutron albedo. There are conflicting data on the absolute value of the albedo itself, although there is now better agreement on neutron fluxes within the atmosphere. Hence a critical review of the techniques employed in neutron experiments is undertaken, and some possible ways of resolving some of the difficulties are suggested. The search for solar neutrons is also described, and some possible solar‐neutron experiments are suggested. In the study of both Van Allen and solar problems, high‐energy neutrons are most interesting, and yet this energy region is the least explo

ISSN:8755-1209    

DOI:10.1029/RG003i003p00345

年代:1965

数据来源: WILEY

摘要:

The exploration of possible engineering uses of nuclear explosives, begun in 1957, has continued and has resulted in substantial progress. Major advances have been achieved in development of much cleaner explosives that will extend the range of possible use and will lead to lower costs. Several nuclear experiments have been carried out which provide an improved technological base from which to assess both cost and feasibility of various projects. The effect of the additional knowledge has been to increase confidence in the feasibility and economic advantage of nuclear excavation, certain underground mining applications, and isotope production for research.

ISSN:8755-1209    

DOI:10.1029/RG003i003p00365

年代:1965

数据来源: WILEY

摘要:

Cumulus dynamics is approached as an experimental science. Its development since 1947 is briefly reviewed and the current convection models described, in particular models evolved from laboratory studies, such as the ‘starting plume’.A preliminary series of experiments on real tropical cumuli has been conducted as a method for testing and improving models and for assessing the range of applicability of the laboratory results. A silver iodide seeding technique was used in a joint U. S. Weather Bureau‐U. S. Navy experimental program called Project Stormfury. Eleven tropical cumulus clouds were probed by instrumented aircraft on four days in August 1963. Six were seeded by dropping pyrotechnic silver iodide generators into their tops at intervals of 100 meters or less; five were studied as ‘controls.’ All control clouds died without further growth. Of the treated clouds, one was seeded by misunderstanding when its top was below 10,000 feet; it collapsed. The remaining five treated clouds grew. Of these, three were seeded at low enough elevations so that natural glaciation was unlikely; these are called the ‘test’ clouds. All three test clouds were observed to ‘explode’ in two phases. The first phase was a vertical growth of 10,000–20,000 ft, occupying 10–12 minutes; the second was a horizontal expansion, with the resulting giant cloud persisting more than 30 minutes. Using laboratory and theoretical results, we construct a dynamic model of the first growth phase and test it against the aircraft measurements and photographic data. The model predicts tower ascent rates, excess temperatures, and water contents, with environment and cloud base conditions as input. It predicts that unmodified clouds could not have attained the observed heights. Furthermore, the postulated effects of seeding (fusion heating, expansion, and altered precipitation fallout) are incorporated into the model and are shown able to account for the excessive growth of the test clouds following treatment. A set of extensive control calculations shows that the main deductions are insensitive to the existing uncertainties in the input data and the modeling assumptions. Improved experiments are suggested to resolve some of the basic questions in cumulus dynamics, as we

ISSN:8755-1209    

DOI:10.1029/RG003i003p00387

年代:1965

数据来源: WILEY