摘要:

The results of a recent investigation are used to help clarify the mechanisms of onset and development of electrical discharge from water‐drop surfaces exposed to a high field. It is shown that the mechanism determining onset need not be that involved in subsequent development. Thus at about atmospheric pressure, the cause of discharge is surface instability; development produces corona. The different onset fields for positive and negative corona should cause negative charging of highly stressed drops even at atmospheric pressure. The recognition of both positive and negative corona processes from water allows explanation of several puzzling observations, including those of Macky (1931

ISSN:0148-0227    

DOI:10.1029/JC075i012p02153

年代:1970

数据来源: WILEY

摘要:

During the summer of 1966, lightning current was measured as it passed through a resistive shunt which was placed at the top of a tower on Mount Lemmon in southern Arizona. A total of five flashes struck the tower; one flash was exceptionally large and transferred over 100 coulombs of charge to ground in 25 separate strokes. Data are presented on stroke rise‐times, peak currents, interstroke time intervals, and current waveform

ISSN:0148-0227    

DOI:10.1029/JC075i012p02159

年代:1970

数据来源: WILEY

摘要:

The magnitude of corona point discharge current was measured in the Cornell Aeronautical Laboratory transonic wind tunnel at speeds ν in meters per second from zero to supersonic, at densitiesDfrom 0.15 to 2.1 atm, at point potentialsVfrom 0 to ±60,000 volts. Direct currents up to 290 μa were observed. At zero speed the current is small, proportional to ion mobility, and quadratic with voltage. At high speeds the current is much greater, approximately linear with voltage and speed, and independent of polarity. Approximately 75% of 1344 data points fit the following expression for currentiin amperes within 10%:In this expression ε0= 8.854×10−12farad/m,D0is atmospheric density at 0°C and 760 torrs,kis ionic mobility (+1.6×10−4or −22×10−4m2/sec volt), andV0is a starting potential of +6860 (D/D0)0.13or −4940 (D/D0)0.22volts. A slightly better fit is obtained if two additional arbitrary constants are used. From a dimensional analysis argument the coefficient 1.785 must include a geometrical dimension (to the grounded electrode or wind tunnel walls) as a term in the denominator. Therefore for a truly isolated point the first t

ISSN:0148-0227    

DOI:10.1029/JC075i012p02165

年代:1970

数据来源: WILEY

摘要:

The velocity distribution and structure function of irregular winds near the 100‐km level are presented. The irregular winds were measured by differencing chemical release wind profiles determined at times different by an integral multiple of 24 hours and by computing the deviations from the 3‐day mean of winds at the same time of day. There is a significant variation of the rms irregular winds between the 90‐ and 115‐km limits over which they were measured. The magnitudes and variations with altitude are found to be reasonably similar for data obtained from Eglin AFB, Florida; Yuma, Arizona; and Barbados, West Indies. The distributions of irregular winds seem to depart slightly from a Gaussian distribution. In particular, a low value of the flatness factor has been measured consistently. The altitude and time structure functions of the irregular winds indicate a characteristic vertical wavelength of about 16 km and time scales of up to 20 hours. The observed structure functions over small scales (2–3 km for the vertical structure function, about 2 hours for the time structure function) follow a power law variation with an exponent value near 3/2. This may result from an energy spectrum of irregular winds that varies as the −5/2 power of wave number an

ISSN:0148-0227    

DOI:10.1029/JC075i012p02171

年代:1970

数据来源: WILEY

摘要:

Measurements of solar radiation at two different elevations in Phoenix, Arizona, yield a mean transmittance difference between the two levels (Δ elevation = 464 meters) of 0.012 for the summer period May through August and 0.066 for the winter period November through February. Theoretical calculations of the transmittance of the atmosphere yield very similar values for these periods, if we assume that most of the atmospheric dust in winter is confined to this surface layer and that atmospheric dust in the summer is more evenly distributed to about 3000 meters. A mechanism is proposed to explain this seasonal variation in the vertical distribution of surface‐generated dust, and local meteorological data are presented to support its validi

ISSN:0148-0227    

DOI:10.1029/JC075i012p02179

年代:1970

数据来源: WILEY

摘要:

This paper is a functional description of the ARL laser profilometer, a special‐purpose laser device built to measure ocean‐wave profiles from an airborne platform. Mounted in an aircraft flying at 60 meters above the surface and at 240 km/hr, the profilometer yields data which are processed to produce a vertical‐section trace of the ocean surface showing ripples of 2.5 cm or less and waves of any h

ISSN:0148-0227    

DOI:10.1029/JC075i012p02185

年代:1970

数据来源: WILEY

摘要:

Simplified models of the time‐dependent propagation of disturbances on glaciers are analyzed. A brief discussion of the application to river flows is included. A one‐dimensional, time‐dependent model including nonlinear convective effects is first presented. A two‐dimensional, time‐dependent model is then discussed and limiting solutions for short‐ and long‐wavelength disturbances are given. It is shown that short‐wavelength disturbances diffuse but do not travel relative to the glacier surface. In the long‐wavelength approximation, the results are similar to the results from the one‐dimensional model but additional details of the flow field are obtained. An elementary model of glacier surge is then presented. Surface height and speed are calculated for specified conditions at the

ISSN:0148-0227    

DOI:10.1029/JC075i012p02189

年代:1970

数据来源: WILEY

摘要:

A study of the dissolved and particulate organic carbon in the Gulf of Mexico showed that mean amounts of both forms were highest in shelf waters (depth less than 100 fathoms), lower in the surface water (0 to 90 meters) of the open gulf, and lowest in the deep open gulf (90 to 3600 meters). An evaluation of the sources of dissolved organic carbon (DOC) in the Gulf of Mexico indicates approximately equal contributions from runoff, in situ generation in open gulf surface water, and a near‐shore source that may result from human activities. Preliminary evidence suggests that DOC will be a useful parameter for understanding the mixing behavior of various water masses in the Caribbean‐Gulf of Mexico syst

ISSN:0148-0227    

DOI:10.1029/JC075i012p02199

年代:1970

数据来源: WILEY

摘要:

A time series of current at 30 meters was measured at 13°08″N, 59°12″W (25 km east of Barbados) from July 1, 1968, through August 30, 1968. The water depth at this site is approximately 2600 meters. A Geodyne model 85OD digital‐tape‐recording current meter was suspended beneath a stable spar buoy [Garstang and LaSeur, 1968]. The buoy provided an exceptionally stable platform for near‐surface current measurement [Warsh et

ISSN:0148-0227    

DOI:10.1029/JC075i012p02207

年代:1970

数据来源: WILEY

摘要:

A new temperature‐salinity plot has been devised to show the relative effect of temperature and salinity changes on the sea water density. On this plot, the lines of constant sigmaTare equally spaced straight lines at an angle of 45°, changes in salinity are horizontal, and changes in temperature are nearly vertical. By plotting the annual changes on this diagram, the relative importance of temperature and salinity variations and their phase relationships can readily be se

ISSN:0148-0227    

DOI:10.1029/JC075i012p02209

年代:1970

数据来源: WILEY