摘要:

The lightning flashes induced by a thermonuclear detonation at Eniwetok Atoll in the Pacific in 1952 are described. The five discharges were upward‐propagating and were apparently initiated from instrumentation stations slightly above sea level. The likely mechanism for the necessary charge and electric‐field generation (Compton electrons produced by gamma rays from the detonation) is explored quantitatively. The electric‐field intensity calculated 3 × 104v/m is near the value needed to initiate lightning from surface projections. The charge estimated to be available, however, appears to be insufficient to account for the observed lightning. Scattered trade‐wind cumulus clouds and spray electrification from the salt water are considered and rejected as charge

ISSN:0148-0227    

DOI:10.1029/JC077i009p01591

年代:1972

数据来源: WILEY

摘要:

Radiometric measurements of upward vertical radiance from the sea surface in the 10‐ to 12‐μm wavelength interval indicate that the water‐vapor absorption coefficient is dependent on water‐vapor content. The observed dependence of water‐vapor absorption coefficient on vapor pressure is in qualitative agreement with the laboratory results of Bignell. At Cairns, in winter, the measured absorption coefficient varies from 0.14 ± 0.04 g−1cm2(10 mb vapor pressure, ∼11°C temperature) to 0.24 ± 0.04 g−1cm2(20‐mb vapor pressure, ∼18°C). The contribution from hygroscopic aerosols appears to be small. Upward radiance profiles were measured through two stratocumulus clouds. The measured vertical emissivities of the clouds were 0.90 (a 560‐meter‐thick deck) and 0.81 (a 220‐meter‐thick deck). Deduced volume absorption coefficients within the

ISSN:0148-0227    

DOI:10.1029/JC077i009p01597

年代:1972

数据来源: WILEY

摘要:

Smoke trails are used to find winds in the upper atmosphere. In the present paper, we study theoretically the motion of smoke trails in winds of constant shear in the case of potential, vorticity, and stratified flows. Some general considerations of the motion of smoke trails are also given.

ISSN:0148-0227    

DOI:10.1029/JC077i009p01610

年代:1972

数据来源: WILEY

摘要:

Acoustic attenuation theory with coefficients obtained by experiment has been used to calculate losses from long range propagation along various paths in a standard atmosphere. Frequency dependence of attenuation has been incorporated into Fourier series approximations of positive phase waves from explosions to obtain net attenuations in terms of explosion yield and burst altitude. For some applications this incorporation improves on estimations from assumption of a single frequency of input. Attenuation results are presented for small 0.45‐kg grenades burst at 30‐ to 90‐km altitudes and for ton and kiloton explosives burst near the ground with waves propagated to 50‐km altitudes and back to the ground near 200‐

ISSN:0148-0227    

DOI:10.1029/JC077i009p01616

年代:1972

数据来源: WILEY

摘要:

An empirical model is presented for explosion wave propagation, which demonstrates that pressure amplitude is inversely proportional to distance raised to the 1.2 power. This model resulted from recordings of vertical propagations, essentially unrefracted by the horizontally stratified atmosphere, and by comparison of amplitudes from different yields after nearly simultaneous propagation along more complex atmospheric paths. Recent NASA rocket grenade experiments provide basis for extending the scaled range of applicability to 8000 km from a 1‐kt nuclear explosio

ISSN:0148-0227    

DOI:10.1029/JC077i009p01623

年代:1972

数据来源: WILEY

摘要:

Measurements were made of size and electric charge of raindrops falling from warm clouds at Hilo, on the windward coast of the island of Hawaii, during November and December 1970. Most raindrops smaller than 1.4 mm in diameter are negatively charged, whereas larger drops are predominantly positive. Rainfall from shallow cumulus clouds most frequently contains negatively charged raindrops. A tentative model is proposed to explain the observed variation in raindrop size and charge during the development of warm clouds over Hawaii.

ISSN:0148-0227    

DOI:10.1029/JC077i009p01630

年代:1972

数据来源: WILEY

摘要:

During May 1967, R. V.Chainsystematically examined a mid‐ocean thermal front in the region between 29°N and 31°N and 68°W and 71°W. A prediction was made aboard ship, based on the theory of Rossby waves, of the change in current direction and of the time this frontal zone would pass through 30°N, 70°W, where a current meter at 10 meters below the sea surface was moored. The current‐meter record revealed a jet‐like structure on June 6, 1967, as predicted, with a central strong current to the southeast corresponding to the frontal passage. Also, the jet‐like current variations that occurred 25–40 days earlier on the record are likely to be associated with another portion of the same meandering westward‐moving Rossby wave. This Rossby‐wave interpretation of the thermal front and the success of the prediction of the current changes at a buoy 10 meters below the sea surface are complicated by the effects of the wind. Nevertheless, the mean flow directions exhibited in the two‐month‐long current record do not appe

ISSN:0148-0227    

DOI:10.1029/JC077i009p01637

年代:1972

数据来源: WILEY

摘要:

A Mach‐Zehnder interferometer was used to study the role of convection currents in the freezing of sea ice. The isotherms are obtained throughout the liquid and from these the convection pattern can be determined. The temperature distribution in the sea water agrees with the calculations by Veronis that show a reversal of temperature gradient in the central portion of the test sections at large Rayleigh numbers. The ice front that forms in undercooled sea water, where there is a temperature gradient, extends to the 0.0°C isotherm. High‐salinity brine is ejected by the sea ice at about 80 sec after freezing for the experiments conducted in this s

ISSN:0148-0227    

DOI:10.1029/JC077i009p01647

年代:1972

数据来源: WILEY

摘要:

A consistent picture of the emission characteristics of sea foam at microwave frequencies has emerged from a survey of published radiometric measurements. The results are summarized, as functions of frequency and angle, by means of simple equations. Available data on the reflection properties of foam are also examined and shown to be qualitatively, but not quantitatively, in agreement with the radiometric results.

ISSN:0148-0227    

DOI:10.1029/JC077i009p01658

年代:1972

数据来源: WILEY

摘要:

The presence of excess4He in deep and bottom waters of the southeast Pacific Ocean, first indicated by results from the Carrousel expedition, has been confirmed in samples from the Piquero expedition of the Scripps Institution of Oceanography. The mean concentration of He in this part of the Pacific and in waters below 2000 meters depth is (4.54 ± 0.01) × 10−5ml (STP)/liter. Helium gradients are observed close to the bottom and below the Antarctic Intermediate Water (AAIW). Their interpretation allows an estimate of the influx of He through the sediment‐water boundary between 1 and 2 × 106atoms/cm2sec. All noble gases are highly supersaturated near the core water of the Equatorial Undercurrent, and the influence of this water is again evident in the Equatorial 13‐C water. The generation of such supersaturated water is suggested to derive from areas of high evaporation although the details are not yet clear. While the mean concentrations of all gases in deep water are in good agreement with the results of the Carrousel expedition, mean surface supersaturations are from 1% to 2% lower, probably due to seasonal effects. Evidence for mixing within the thermocline is absent in the Piquero

ISSN:0148-0227    

DOI:10.1029/JC077i009p01667

年代:1972

数据来源: WILEY