摘要:

Observations at a wavelength of 1.82 cm (16,500 Mc/s) with the University of Michigan's 85‐foot radio telescope were made of the total lunar eclipses of December 30, 1963, June 25, 1964, and December 18, 1964. Results of the first two eclipses were inconclusive because of atmospheric and ground effects at the large zenith distances at which the eclipses occurred and inability to observe the entire eclipse. A full eclipse curve was‐obtained at small zenith distances on December 18, 1964. The measured decrease in emission during this eclipse was 4.1±0.7% of the central disk temperature after corrections for side‐lobe effects. This corresponds to a change of 10±2°K for an assumed central surface brightness temperature of 240°K. Duration of the total eclipse phase of the center of the moon was 130 minutes. The delay in the minimum of the λ1.82‐cm eclipse curve from the optical eclipse curve was not detectable within the observational uncertainty of 10 minutes. This is the longest wavelength at which a change has been reported in the radio emission from the moon during a l

ISSN:0148-0227    

DOI:10.1029/JZ071i014p03339

年代:1966

数据来源: WILEY

摘要:

Rain and hail data from five meteorological stations on the plateau of South Africa have been examined for a dependence on lunar phase. Different distributions with respect to lunar phase were found for summer and winter data. Statistical analyses of the winter distributions, which appeared to be more significant than those for the summer, suggested that winter rain is modulated by the moon in such a manner that there is one component with the same period as the lunisolar cycle which depends on station latitude and another having three peaks which is latitude independent. This three‐peak component seems to operate throughout the yea

ISSN:0148-0227    

DOI:10.1029/JZ071i014p03345

年代:1966

数据来源: WILEY

摘要:

Freezing of supercooled water drops has been studied by a constant‐temperature method to determine the dependence of heterogeneous nucleation on temperature and on the duration of supercooling. A polished metal surface, coated with a water repelling film of liquid paraffin, is used to support the rain‐sized water drops being frozen. Complex and rather unexpected behavior was observed during initial freezing after sudden chilling. However, the latter part of the freezing process agrees with the equation developed from the probability considerations by Bigg and shows time dependence. The complex parts of the curves obtained during initial freezing can be explained by the recently discovered dependence of freezing temperature of supercooled drops on rate of cool

ISSN:0148-0227    

DOI:10.1029/JZ071i014p03351

年代:1966

数据来源: WILEY

摘要:

Periodic and height‐dependent solutions are derived for the disturbances of concentrations of Rn222, Rn220, and their first three decay products in the air above the earth's surface, account being taken of turbulent diffusion and radioactive decay. At the surface, sinusoidal oscillations of Rn222and Rn220are assumed, but the concentrations of decay products are required to vanish. At large heights, all concentrations are required to vanish. It is shown that the Rn222(radon) concentration disturbance is influenced mostly by turbulent diffusion and only slightly by decay. The form of the disturbance is very similar to that of the diurnal oscillation of potential temperature for a constant eddy conductivity. Amplitude decreases exponentially upward and phase propagates upward with constant velocity. Daughter products near the surface are not, by reason of the lower boundary condition, in radioactive equilibrium with Rn222. At sufficiently large heights, however, all daughter products approach radioactive equilibrium with Rn222by reason of their rapid decay. The height at which radioactive equilibrium becomes a good approximation increases with each successive decay product and ranges from tens to hundreds of meters in numerical examples. These results suggest that the inference of Rn222concentrations from experimentally determined concentrations of its decay products is not justified except at great heights. The Rn220(thoron) concentration is strongly influenced by decay as well as by turbulent diffusion. The concentration disturbance attenuates and propagates rapidly upward at exponential and constant rates. Since Po216decays even more rapidly than Rn220, these two approach radioactive equilibrium at sufficiently large heights. Pb212decays much more slowly than its precursors, so that it is not in radioactive equilibrium with them at any height. Amplitude attenuation and phase propagation are similar in form to those of the enthalpy disturbance. Since Bi212decays more rapidly than Pb212, these two approach radioactive equilibrium at great height

ISSN:0148-0227    

DOI:10.1029/JZ071i014p03357

年代:1966

数据来源: WILEY

摘要:

The CO2content of a gas phase equilibrated with the assemblages nahcolite + trona + solution, nahcolite + trona + halite + solution, and trona + thermonatrite + solution has been determined at 1 atm pressure, using an infrared method. Equilibrium was approached from both sides. Between 20 and 60°C, the CO2content of the gas for the assemblage nahcolite + trona + solution + gas varies from 1475 to 20,300 ppm, and that for the assemblage trona + thermonatrite + solution + gas changes from 20 ppm at 40°C to 435 ppm at 70°C. These results were applied to the Eocene Green River formation and the Pleistocene Searles Lake deposits. In both cases, it is concluded that the CO2contents of the paleoatmospheres must have been within the range specified by the trona + solution assemblage, that is, between 10 times and 1/10 of the CO2content of today's atmosphe

ISSN:0148-0227    

DOI:10.1029/JZ071i014p03369

年代:1966

数据来源: WILEY

摘要:

Unrecrystallized fossil corals occurring in their growth positions between 2 and 9 meters above sea level at many locations in the Pacific and Indian oceans have been dated by the Th230/U238and U234/U238methods. Where possible, recent corals were also collected and analyzed for their uranium and thorium isotopes. The uranium contents of the corals were determined fluorimetrically; the U234/U238ratios and the thorium concentrations were ascertained by alpha spectrometry. The Th230/U238ages of the fossil corals range from 90,000±20,000 to 160,000±40,000 years and the U234/U238ages from 80,000±50,000 to 180,000±60,000 years. Absence of Th230in the recent corals and absence of Th232in both the recent and the fossil corals confirm the assumption that the Th230found in the fossil corals resulted solely from radioactive decay of its parent uranium. Control samples of pre‐Pleistocene material showed radioactive equilibrium between the various members in the U238decay chain. Both the internal consistency of the ages, within experimental error, and the agreement between the Th230/U236and U234/U238ages, strongly support the general validity of these ages. The similarity of the Th230/U238ages of Pleistocene coral reefs to those of like elevations above sea level in many localities suggests a eustatic sea level stand higher than now at about 120,000±20,000 years ago, possibly during an interglacial stage of the Pleis

ISSN:0148-0227    

DOI:10.1029/JZ071i014p03379

年代:1966

数据来源: WILEY

摘要:

The experimental techniques used for measuring thermoluminescence are described. The glow curves of achondrites differ markedly from subclass to subclass in their artificially excited glow curves. A fair correlation exists between the radiation ages and the luminescence intensity. The olivine components of pallasites yield very low luminescence whereas the silicate components of mesosiderites (with the exception of Weatherford) exhibit distinct peaks at about 90°C. To a good approximation the luminescence intensity of the chondrites is proportional to their radiation ages. If a correction for the radiogenic part of the thermoluminescence is applied, approximate radiation ages can be estimated from thermoluminescence data

ISSN:0148-0227    

DOI:10.1029/JZ071i014p03387

年代:1966

数据来源: WILEY

摘要:

Spherules found in snow crystals, ice‐fog crystals, fallout particles, and fly ash were studied with an electron microscope using the electron diffraction method. The central part of the residues of 1004 specimens of natural snow crystals from Greenland, the United States, and Japan were examined; 14 spherules 0.1 to 1.5 μ in radius were found among them. The residues of 658 artificial ice‐fog crystals formed from water vapor in flue gases of coal‐burning electric power plants at Fairbanks, Alaska, were also examined; 9 spherules were found. Spherules similar to those found in ice‐fog residues were found in furnace‐produced fly ash fallout. Electron and optical microscope examination of spherules found in Greenland snow reveals a size distribution of the formdN/d(logr) =Cr−βwhere β ≈ 3. The properties of spherules and mean mass of snow crystals in Greenland are described. The electron microscope study indicated that less than 0.7% of the 1004 snow crystals contained spherules of possibly extraterrestrial origin and that snow crystals are formed mainly on clay mineral particles by heteroge

ISSN:0148-0227    

DOI:10.1029/JZ071i014p03397

年代:1966

数据来源: WILEY

摘要:

The Salmon nuclear detonation of October 22, 1964, had a nuclear yield of 5.3±0.5 kt. The teleseismic magnitude was 4.35.Pwaves observed out to 2500 km show asymmetries in the propagation, with high amplitudes (mμ/sec), faster apparent velocities, and higher signal frequencies to the north and northeast than to the west. At teleseismic distances, many of the signals were very weak and could be identified with Salmon only because the time of detonation and expected arrival time were known. If a cavity were built of a size to fully decouple 5 kt at the Salmon site, theoretical calculations which include the nuclear shock predict a decoupling factor of about 170 or a magnitude of 2.1. If such a cavity were used for partially decoupling a 25‐kt shot, the magnitude is predicted to be 3.1. Drilling back into the Salmon shot region revealed a standing shot cavity of 20,000 m3, corresponding to a sphere of radius 17 met

ISSN:0148-0227    

DOI:10.1029/JZ071i014p03405

年代:1966

数据来源: WILEY

摘要:

Calculations (SOC computer code) of shock pressure, position, velocity, and material displacement have been made for the Salmon detonation (design yield of 5 kt) based both on results from the Gnome event (3.1 kt in salt) and physical properties measurements of the material in the shot region. Comparison of the calculations with experimental data gives agreement for peak pressure and peak velocity within 20 to 50% over the range calculated (1 to 600 meters). Calculations and observations agreed to within 1 to 10% for shock wave arrival times, to 25% for displacement of the salt at 300 meters, and to within 10 to 50% for ground surface motion directly above the shot. The calculations based on physical properties measurements from the shot region generally gave better agreement with the data than those extrapolated from the Gnome event. The central cavity apparently grew to a radius of 24 m during the initial dynamic stage and then contracted back to a radius of 17 meters after the shot.

ISSN:0148-0227    

DOI:10.1029/JZ071i014p03415

年代:1966

数据来源: WILEY