摘要:

Formation of dust clouds observed in the Martian atmosphere can be explained by the action of dust devils larger than 100 meters in diameter. The condition for the onset of thermal convection is the existence of an unstable temperature profile. The daily variation of the atmospheric temperature profile shows that the Martian atmosphere is more favorable for the initiation of dust devils than the earth's atmosphere. The calculations indicate that dust devils on Mars produce wind velocities only slightly lower than those on earth.

ISSN:0148-0227    

DOI:10.1029/JZ071i010p02419

年代:1966

数据来源: WILEY

摘要:

The possibility of a terrestrial origin of tektites is re‐examined in the light of recent aerodynamic evidence presented by Chapman, Larson, and Anderson. It is found that even though existing evidence points strongly toward a lunar origin as most probable for Australasian tektites, there still exists the possibility that these small glassy objects originated on the earth. In particular, it is conceivable that a sufficiently energetic cometary collision of the type hypothesized earlier by Urey could momentarily blow a bubble through the earth's atmosphere and hence propel small objects over intercontinental distances. The minimum mass of a comet head required to accomplish such a feat is estimated to be about 5×1017grams. Some obvious questions which remain to be answered in order to support such a model of tektite origin are discuss

ISSN:0148-0227    

DOI:10.1029/JZ071i010p02427

年代:1966

数据来源: WILEY

摘要:

Large‐ and small‐scale atmospheric eddy velocities and scale lengths are estimated using previously measured values of ϵ (the rate of dissipation of turbulent kinetic energy) and υ2(the square of the contaminant dispersion velocity). The estimated values are based upon the assumption that the wave numberskdominating the dispersion are within the ‘inertial’ subrange, where the rate of flow of turbulent kinetic energy is conserved over this range. Also estimated is the large‐scale eddy Reynolds number (defined here), which is shown to approach unity at the limiting altitude of atmospheric

ISSN:0148-0227    

DOI:10.1029/JZ071i010p02439

年代:1966

数据来源: WILEY

摘要:

Radiosonde data for latitude 60°N have been combined with available meteorological rocket wind and temperature observations at Fort Churchill, Canada (59°N), and Fort Greely, Alaska (64°N), in order to estimate the annual stratospheric temperature regimes between 25 and 55 km at 75°N. Using the thermal wind relationship, mean monthly temperatures were extrapolated northward by 5‐km altitude intervals from 60 to 75°N. Resulting temperature patterns at 75°N compare favorably with observed values at radiosonde altitudes. Above 30 km, however, temperature regimes must be considered speculative, since, at 75°N, observations at these heights are almost nonexistent. The annual temperature at lower latitudes increases in amplitude with distance from the equator. In this study harmonic analyses reveal that this pattern continues at all levels into the polar regions. The annual range of mean monthly temperatures, based on estimated values for 75°N and observed values at 60 and 30°N, also increases from 30 to 75°N. The height at which the earliest maximum temperature occurs in the annual cycle lowers toward the pole, probably reflecting the height of the effective top of the stratospheric ozone layer between

ISSN:0148-0227    

DOI:10.1029/JZ071i010p02445

年代:1966

数据来源: WILEY

摘要:

The radiostrontium data obtained at Fayetteville, Arkansas, show that a considerable fraction of the debris from the October 16, 1964, nuclear explosion has entered the stratosphere. It is estimated that the stratospheric Sr90inventory has increased by 0.38% and the tropospheric Sr90inventory by 4.0% as a result of the Chinese nuclear explosion. The mean residence time of Sr90in the troposphere was calculated to be 30 days, according to the two‐compartment model of the atmospher

ISSN:0148-0227    

DOI:10.1029/JZ071i010p02451

年代:1966

数据来源: WILEY

摘要:

Aerosol particles in Cambridge, Massachusetts, were collected by cascade impactor and analyzed for chlorine, bromine, and iodine by neutron activation and for lead electrochemically. The Casella four‐stage impactor selected particles of radius greater than about 0.2–0.5 μ, and two sampling sites were chosen on the M.I.T. campus—on the roof of the 90‐meter‐high Green Center for Earth Sciences and at the curb by a busy street. The ranges 1 to 6 μg Cl/m3STP and 2 to 10 ng I/m3STP are in good agreement with observations in unpolluted Hawaii air, but the range 20 to 800 ng Br/m3STP stands an order of magnitude higher and agrees with observations in Washington, D.C., polluted air. Lead concentrations are 0.1 to 2.2 μg Pb/m3STP and are strongly correlated with high Br concentrations during hazy weather (low visibility) and/or curb‐site sampling. The data suggest that the initial exhaust product is a particulate lead halide which suffers loss of Br in

ISSN:0148-0227    

DOI:10.1029/JZ071i010p02457

年代:1966

数据来源: WILEY

摘要:

The rate of crystallization of supercooled water in cylindrical tubes is determined. It is found that the rate depends on the tube diameter, on the degree of supercooling, and on the thermal conductivity of the wall, but in no simple way. It is shown that no one mechanism of crystallization can account for the growth curves obtained but that a competing process between the heat conduction through the tube wall and the kinetic behavior of the liquid molecules must be considered. The various ice structures observed during the experiment are reported, along with their possible correlation with the observed growth rates.

ISSN:0148-0227    

DOI:10.1029/JZ071i010p02465

年代:1966

数据来源: WILEY

摘要:

The daily variation of lake level is computed from 6 months' hourly data at several gage locations on Lake Erie. The dominant characteristic of this variation is a diurnal constituent of longitudinal oscillation of the lake as a whole, with Buffialo high water and Toledo low water at about noon. The amplitude of this oscillation is about 1.5 cm. A similar analysis is made of the daily variation of the surface wind vector at several anemometer locations on the periphery of the lake. The results show that there is a distinct diurnal constituent of the longitudinal component of the wind‐square vector, with maximum in the direction Toledo to Buffalo shortly after noon. This variation is associated with the normal, convective pulsation of the atmospheric boundary layer. It has an amplitude of about 10 m2sec−2. To examine the mechanics of meteorological and gravitational tides on Lake Erie, computations are made of the response of the lake to a periodic force, by numerical integration of the hydrodynamical channel equations. All evidence is consistent with the hypothesis that the 24.00‐hr constituent of lake level is caused almost entirely by wind stress. On the other hand, the 12.00‐hr constituent is affected significantly by the gravitational tidal force, as well as by the wind stress. (In both constituents the contribution of the atmospheric pressure‐gradient force is negligible.) An earth‐tide correction is applied to the semidiurnal response by means of Jeffreys' values for the L

ISSN:0148-0227    

DOI:10.1029/JZ071i010p02471

年代:1966

数据来源: WILEY

摘要:

The semidiurnal lunar tidal energy flux into shallow seas as derived from harmonic analysis of tidal height and tidal currents is between 1.4×1019ergs/sec and 1.7×1019ergs/sec. The error in this estimate could be as large as half the valu

ISSN:0148-0227    

DOI:10.1029/JZ071i010p02485

年代:1966

数据来源: WILEY

摘要:

The movements of deep water at 27°56′N, 55°22′W, were studied by means of instrumented neutrally buoyant floats. Five such floats were dropped together. They settled at slightly different depths near the 2300‐meter level. The center of this cluster moved in a curved path to the southeast at an average speed of 2 cm sec−1. One of the floats, 140 meters deeper than a second one, moved relative to the second float in an almost circular path approximately 2 km in diameter and with an orbital velocity of 8.2 cm sec−1and period of 25.2 hours. Variations in temperature amounting to ±0.02°C took place at a float. The variations in depth, approximately 4 m, rms, implied vertical water movements of 14 m rms. Spectrums were obtained for the variations of depth, temperature, and separation between two floats with time. The vertical temperature profile of the water was obtained from the temperature and depth data transmitted by a float which was made heavy enough to sink slowly to the bottom. The temperature gradient found was not monotonic with depth even near the bottom. An analysis of the characteristics of internal waves suggests that such waves caused most of the wa

ISSN:0148-0227    

DOI:10.1029/JZ071i010p02491

年代:1966

数据来源: WILEY