摘要:

The response characteristics of the height‐based and time‐based wind reduction techniques for meteorological rocketsondes are deduced for the region 20–55 km by use of analytical expressions for position and time as functions of height. It is shown that the height‐based method is more consistent in depicting medium‐scale perturbations than is the time‐based method. This is accomplished, however, at the expense of the simplicity of the time

ISSN:0148-0227    

DOI:10.1029/JC074i028p06853

年代:1969

数据来源: WILEY

摘要:

The discharge‐onset potential of water surfaces 0.022 to 0.146 cm in radius has been measured over a range of pressures corresponding to altitudes in the standard atmosphere of 1 to 13 km. The transition from the surface‐disruption mode of discharge to pure corona has been observed for both positive and negative surfaces. The positive transition occurs at an altitude of about 4.5 km; the negative transition occurs at about 7.0 km. Between these two points, the products of discharges are mostly positive ions and negative droplets. Furthermore, the different onset potentials for the two polarities cause any drop exposed to a high enough field, regardless of direction, to be left with a large negative charge. These results should be true quite generally, regardless of the source of the surface electric fi

ISSN:0148-0227    

DOI:10.1029/JC074i028p06859

年代:1969

数据来源: WILEY

摘要:

An evaluation is made of the resolution of a modified Ehmert apparatus for measuring ozone profiles in the atmospheric surface layer. Comparisons between instruments suggest a resolution capability for difference measurements by two instruments of the order of ±1.4 μg m−3of ozone. Typical differences in ozone concentration between 16‐ and 1‐meter height are observed to be 3–4 μg m−3during conditions of strong daytime mixing. It follows that the Ehmert method may be used to measure ozone differences and determine ozone fluxes during representative atmospheric conditions; such measurements have hitherto been considered

ISSN:0148-0227    

DOI:10.1029/JC074i028p06869

年代:1969

数据来源: WILEY

摘要:

The ozone content of the mesosphere and stratosphere was measured at Wallops Island, Virginia, on September 16, 1968, by using a newly developed parachute sonde released from a rocket. The sonde determines ozone mixing ratio, in situ, as a function of altitude by means of a sensor containing a chemiluminescent detector. The atmosphere is sampled by self‐pumping as the sonde descends on a specially designed high‐altitude parachute. Calibration of the ozone sensor is accomplished immediately prior to flight by sampling known concentrations of ozone at rates expected during a flight. An ozone profile of approximately 2‐km resolution was obtained from 67 to 18 km. A small secondary peak was measured at approximately 62 km. An ozone mixing‐ratio maximum of 16 μg/g was measured at 34 km, and a concentration peak of 5 × 1012molecules/cm3was measured at 25 km. The estimated error in the measurement between 57 and 20 km is about ±20%, and about ±50% at the other altitudes. The chemiluminescent sonde‐measured profile agrees well with other rocket and balloon observations flown simultaneously with this flight in the altitude regions in which the measure

ISSN:0148-0227    

DOI:10.1029/JC074i028p06873

年代:1969

数据来源: WILEY

摘要:

Large amplitude vibration of water drops was investigated theoretically and experimentally. Upon entering a static electric field, the drops began to oscillate. When the frequency of a fluctuating field was varied, a frequency was found for which large amplitude vibrations set in. This resonance frequency decreased as the amplitude increased and when the drop was stretched in a static field. In all the fields the water drops broke up when the field strength was sufficiently large. For smaller drops the breakup occurred at a considerably lower field strength in the fluctuating fields than in the static. In fluctuating fields, breakup occurred by shedding a small fragment from each end of the elongated drop. For larger drops, breakup field strength was about the same for all fields.

ISSN:0148-0227    

DOI:10.1029/JC074i028p06881

年代:1969

数据来源: WILEY

摘要:

It is postulated that ball lightning is initiated by a lightning stroke that forms a large sphere of heated material. The following models are considered: (1) cooling spheres of air; (2) cooling spheres of air containing small amounts of sodium vapor; (3) cooling spheres of mixtures that are by weight (a) carbon vapor andair or (b) copper vapor andair. For each model calculations are made of the temperature profiles, output radiation, and average mass density as a function of time, taking account of energy transfer due to conduction, radial convection, and emission and absorption of radiation. Models 1 and 2 are deficient in explaining the properties of ball lightning in that the spheres are lighter than the surrounding air and thus rise. With model 3, although the average mass density can approximate that of air so that the ball does not rise, there is insufficient emission of visible radiation. It is possible, however, that chemical processes, which are not considered in the present calculations, occur at the boundary of the sphere of suspended particles and the surrounding air and give relatively constant emission of light.

ISSN:0148-0227    

DOI:10.1029/JC074i028p06887

年代:1969

数据来源: WILEY

摘要:

The magnetic flux density due to first and to subsequent lightning return strokes is calculated for distances from the strokes of 0.5 to 200 km. The basis of the calculations is various assumed forms for the channel current as a function of time and of channel height. Two new channel‐current models are introduced for first strokes and one new model for subsequent strokes, in addition to the use of the models of Bruce and Golde and of Dennis and Pierce. The new models provide a better approximation to the real lightning channel current than do the previous models, but all models considered yield radiation fields far from the channel that are consistent with experiment. It is shown that, contrary to the claims of Norinder and co‐workers, the magnetic‐field rise time for a stroke within a distance of about 20 km is essentially unrelated to the current rise time in the stroke channel base. For subsequent strokes, field rise times of many tens of microseconds can be due to current rise times shorter than a microsecond. On the other hand, field rise times for subsequent strokes may be strongly influenced by current fall times. The analysis of Norinder and co‐workers which relates peak channelbase current to peak magnetic field yields values of current that can be considered accurate to about a fact

ISSN:0148-0227    

DOI:10.1029/JC074i028p06899

年代:1969

数据来源: WILEY

摘要:

Charged aerosol clouds emerging from supersonic nozzles have been used to induce electrical breakdown from large falling drops of water. As expected, it is shown that only positive streamers are produced independently of the polarity of the aerosol. These streamers are not suppressed by spray from the drop, and their propagation is enhanced through negative aerosols. Two interacting jets have been used to produce very high concentrations of aerosol space charge in a region far removed from any electrodes. For positive charge this region behaves like a positive corona discharge. For negative charge the local negative streamer breakdown produced invokes either positive streamers or actual sparks from nearby regions depending on the charge density of the aerosol. The physical mechanism required for the explanation of the results obtained completely agrees with, and supports, Loeb's recent theory for the formation of stepped leaders in lightning discharges. It is shown that breakdown between positive and negative aerosols can also be obtained by means of interacting jets.

ISSN:0148-0227    

DOI:10.1029/JC074i028p06911

年代:1969

数据来源: WILEY

摘要:

A model for the sound generated by a tortuous lightning channel is proposed that describes the principal features of thunder. The model indicates that the power spectrum of thunder should be similar to the power spectrum produced by a short line segment having the same energy‐per‐unit lengthElas the most energetic return stroke in the lightning flash. This model also predicts thatElcan be estimated from a measurement of the frequency of the peak in the power spectrum of thunder ƒm; the relationship is ƒm= (0.63)C0(P0/El)1/2, whereP0andC0are the ambient pressure and sound

ISSN:0148-0227    

DOI:10.1029/JC074i028p06926

年代:1969

数据来源: WILEY

摘要:

Simultaneous measurements of the vertical fluxes of ozone and heat were made near Albuquerque, New Mexico, in 1968, together with measurements of the vertical profiles of ozone and temperature in the first 16 meters above the surface. The eddy flux of ozone was determined by a new method using the decay of ozone in a box with open bottom, placed on the ground. The eddy flux of heat was determined as the difference between the net radiative flux and the soil heat flux. The vertical distributions of ozone, temperature, and wind were measured with sensors mounted on a platform that was raised and lowered electrically along a 16‐meter tower. The profiles and the flux values are used to compute coefficients of eddy diffusivity of ozone and heat. The results show that measurements of the ozone flux and of the ozone gradient can be used for determinations of the eddy transport of atmospheric properties in low‐wind situations, whenever measurements of temperature or wind profiles, and of the related fluxes, are not practi

ISSN:0148-0227    

DOI:10.1029/JC074i028p06935

年代:1969

数据来源: WILEY