摘要:

Recent observations indicate the rather complete neutralization of volume space charges by induced positive corona streamers. New photographic observations of high‐tension power lines in rain and snow storms reveal strong and heavily branched corona streamers from such hydrometeors. A study of uniform field streamer breakdown in midgap in clean gases, just published, has provided additional information essential to the delineation of the processes active in the forging of the channel of the cloud‐to‐ground stroke. On the basis of these findings, consistent sequential qualitative analysis is presented resolving the following moot questions: 1. How is the negative charge stored on raindrops in cubic kilometers of cloud volume drained and channeled to yield a pilot leader channel some meters in diameter? 2. How is this hydrometeor‐supported discharge able to leave the cloud base and forge into clean, initially un‐ionized air to give a stepped leader? 3. What causes stepping? 4. How is the channel several kilometers in length maintained conducting for the tens of milliseconds needed for it to reach ground? 5. How is it that the stepped leader of some meters diameter leads to a return stroke channel with the most intense luminosity millimeters in diameter and the larger luminous conducting envelope no more than 4 cm in diameter? 6. Why is the pilot leader channel zigzagged? 7. What starts the dart leader stroke and how is the channel maintained conducting for the tenths of seconds between successiv

ISSN:0148-0227    

DOI:10.1029/JZ071i020p04711

年代:1966

数据来源: WILEY

摘要:

Balloon‐borne radiometers have been used in a series of observations of thermal emission by terrestrial molecular oxygen, principally by theN= 9+resonance line at 61.151 Gc/s. Observations were taken at two zenith angles (60° and 75°) and at three frequencies (±20, ±60, and ±200 Mc/s) centered on the resonance line during the ascent, float, and descent stages of the flights. Float altitude was approximately 30 km. The results of four flights, launched on February 9, July 23, October 29, and November 8, 1964, from the balloon base of the National Center for Atmospheric Research, Palestine, Texas, are described. The observations appear to be inconsistent with the Van Vleck‐Weisskopf line‐shape theory and/or the laboratory measurements of the

ISSN:0148-0227    

DOI:10.1029/JZ071i020p04723

年代:1966

数据来源: WILEY

摘要:

Direct measurements of Rn220(thoron) have been made from the ground surface to a height of 50 cm, using apparatus adapted from that of G. W. Israël. Activity profiles are similar to those calculated by Jacobi and André and by Wormell; this supports their assumption that in the 50‐cm height range a linear increase of diffusivity with height property describes the turbulent diffusion of radioactive emanations from the soil surface, at least for turbulence of moderate intensity. The maximum activity at ground level, as expected, occurs at night during intervals of very low wind speed; it reaches values 75 to 150 times as high as the typical activities at 50 cm and 1 m. The Rn220flux through the soil surface at our site is approximately 2.1×10−15curie cm−2sec−1, or 0.006 atom cm−2sec−1. The activities of Rn220plus Po216observed under conditions of very low turbulent diffusion are capable of yielding an ion production rate of about 250 ion pairs cm−3sec−1in the lowest 10 cm of the atmosphere over appreciable time intervals; this seems adequate to explain the presence of the shallow stratum of relatively high space charge density previously reported to exist unde

ISSN:0148-0227    

DOI:10.1029/JZ071i020p04735

年代:1966

数据来源: WILEY

摘要:

A program was developed for emission, collection, and analysis of the radioactive rare gas Xe133as an atmospheric tracer. The value of this type of tracer lies in its inert characteristics and our ability to follow the diffusion processes without regard for many of the factors influencing other tracers. Field experimentation using this technique in collaboration with other more commonly used tracers allows correction factors to be developed for the less ideal tracers.

ISSN:0148-0227    

DOI:10.1029/JZ071i020p04743

年代:1966

数据来源: WILEY

摘要:

Total atmospheric attenuation has been measured at 3.2 Ghz, where the attenuation is due primarily to nonresonance absorption of molecular oxygen. The experimental techniques of radio astronomy were used to obtain effective antenna temperatures for discrete sources at various angles of elevation. The result for vertical incidence is 0.042 db. An examination of the possible sources of error indicates that an appreciable systematic error is improbable; the accuracy of the experiment is estimated as ±0.004 db probable error

ISSN:0148-0227    

DOI:10.1029/JZ071i020p04749

年代:1966

数据来源: WILEY

摘要:

The information obtainable from monthly mean sea level records and the joint variation of sea level, atmospheric pressure, and sea temperature are analyzed. The spectrum of sea level is time invariant and shows significant peaks only at frequencies corresponding to the annual and semiannual oscillations. The bispectrum of sea level indicates a weak interaction of the annual frequency with itself, as well as with other frequencies. Secular sea level changes along the Pacific coast are related to land subsidence and uplift. The mean duration of positive and negative sea level anomalies from long‐term monthly means is of the order of 3 months. Extreme durations vary between 10 and 34 months and are closely related to largescale atmospheric disturbances. The areal coherence of nonperiodic sea level fluctuations is of the order of 1200 km. At temperate and high latitudes there is good coherence between nonperiodic sea level and atmospheric pressure oscillations. The response between these two variables varies from −0.9 cm/mb to −2.3 cm/mb in the frequency range between 1 and 6 cycles per year. The coherence between nonperiodic sea level and sea temperature fluctuations is high in tropical latitudes and low in polar latitudes. The response is largely independent of frequency, varying from 1.0 to 2.7 cm/°C. These findings are in agreement with the coefficient of thermal expansion of seawater and the depth of the mixed

ISSN:0148-0227    

DOI:10.1029/JZ071i020p04755

年代:1966

数据来源: WILEY

摘要:

A simple isostatic model explaining the pattern of deformation of the shorelines of proglacial lakes has been developed. The rate of glacial retreat before the formation of the shoreline can be derived from the curvature of its uplifted portion. The rate calculated in this way for the retreat preceding the formation of Lake Algonquin is 120 km/103yr, a value not in conflict with the radiocarbon chronology for this interval. The agreement between the uplift predicted at the iceward extreme of the shoreline (260 meters) and the actual maximum uplift (250±50 meters) provides an independent check on the validity of the model. If the model proves to be correct, the implications are as follows. (1) The continental ice sheets had shapes and total thicknesses during their retreat phases not dissimilar to those observed for present‐day ice masses on Greenland and Antarctica, i.e., dynamic equilibrium was maintained; (2) rebound at the edge of large continental ice sheets is a simple isostatic process occurring with the Washburn‐Stuiver time constant of about 700 years; and (3) the strength of the crust is sufficiently small to prevent the lateral influence of a continental ice sheet from extending more than a few tens of kilometers beyond its mar

ISSN:0148-0227    

DOI:10.1029/JZ071i020p04777

年代:1966

数据来源: WILEY

摘要:

Two forms of the equation of flow of a compressible liquid in an elastic porous medium are derived by considering mass conservation in (1) a control volume whose boundaries are fixed in space and (2) a control volume that deforms and moves through space when the material deforms. The first method yields a form of the equation that necessarily involves the velocity of the grains of the medium. The second yields a form that does not involve the grain velocity. Jacob's equation is found to be correct when negligible terms are omitted.

ISSN:0148-0227    

DOI:10.1029/JZ071i020p04785

年代:1966

数据来源: WILEY

摘要:

The nonsteady flow toward a well open to two aquifers of different hydraulic properties is analyzed. Exact solutions to the problem are found to be intractable for numerical calculations. Therefore, asymptotic solutions which are amenable to easy computation and which yield results accurate enough for practical applications are developed. These solutions make possible the prediction of pumping levels and yields of two‐aquifer wells. They also provide a basis for predicting the hydraulic head changes around such wells and the contribution of each aquifer to the total discharge of the wel

ISSN:0148-0227    

DOI:10.1029/JZ071i020p04791

年代:1966

数据来源: WILEY

摘要:

The paper appraises an analytical study of nonsteady flow to multiquifer wells by means of the flow in a horizontal Hele‐Shaw apparatus. Design and calibration features of the analog are described in detail for a well which penetrates two parallel overlying aquifers of infinite extent. The agreement between analytical solutions derived from a mathematical model, neglecting well losses, and experimental results from the physical analog is found to be very goo

ISSN:0148-0227    

DOI:10.1029/JZ071i020p04799

年代:1966

数据来源: WILEY