Robert V. Anderson

Electricity in Volcanic Clouds Investigations show that lightning can result from charge-separation processes in a volcanic crater

In November of 1963 an oceanic volcano produced an island, Surtsey, just off the southern coast of Iceland. The volcanic crater was often flooded with sea water. Vigorous eruptions of steam and tephra were accompanied by an enhancement of the normal fine-weather potential gradient, and lightning was often observed. Measurements of atmospheric electricity and visual and photographic observations lead us to believe that the electrical activity is caused by the ejection from the volcano into the atmosphere of material carrying a large positive charge. The concentration of charge in the eruption plume as it issued from the orifice of the volcano is estimated to be of the order of 105 or 106 elementary charges per cubic centimeter.

Improved Field Meter for Electrostatic Measurements

An instrument system for the measurement of electrostatic fields is described. The use of more than 40 dB of negative feedback in the amplifier results in a sensitivity stable to within 1%. Careful attention to grounding and to surface preparation in the transducer head results in a zero level stable to within 1 V/m in ideal conditions. The effect of atmospheric variations in limiting the usable sensitivity is demonstrated.

ATMOSPHERIC ELECTRICITY MEASUREMENTS AT WALDORF, MARYLAND DURING THE 7 MARCH 1970 SOLAR ECLIPSE.

Abstract The Waldorf observatory for atmospheric electricity is described. Data are presented in which strong perturbations are produced by the action of the eclipse. It is shown that the diminution and subsequent restoration of eddy turbulence near the ground can produce effects of the type observed if adequate consideration is given to the existing electrical state of the atmosphere during the fully developed turbulence prior to the eclipse.

Measurements of total current density above active snowstorms

Abstract Measurements have been made from an aircraft of the total vertical current density above precipitating snowstorms. Enhanced ‘fair weather’ currents were observed in all but one case where apparently there was a circulating current. These results are discussed in relation to charging processes.

Atmospheric electricity, turbulence and a pseudo-sunrise effect resulting from a solar eclipse

Abstract Recordings made of several atmospheric electric parameters at the Naval Research Laboratory, Waldorf, Md. observatory during the eclipse of 7 March 1970 showed variations similar in nature to classical descriptions of the so-called sunrise effect. The recording of space charge density was spectrally analyzed with the fast Fourier algorithm, and the resultant power spectra were fitted to a power law spectral decay model. Since the decay exponent in this model is related to the fractions of the space charge resident on large and small ions, it is then possible to follow time variations in small-to-large ion ratios through the period of the eclipse. It is shown that the variations in the recorded atmospheric electric variables and in the spectral decay exponent are consistent with a strong diminution of turbulence near the ground as the Sun is obscured and the establishment of a thin layer above the ground in which a higher than normal density of small ions is produced by surface radioactivity. The subsequent resumption of turbulent mixing carries these ions upward, producing the ‘sunrise effect’ variation pattern. The rapidity with which heating is restored is seen to be responsible for those differences in behavior which are observed. It is concluded that eclipse conditions provide a unique opportunity to investigate phenomena which are strongly influenced by atmospheric turbulence.

Aircraft measurements of the geomagnetic latitude effect on air-earth current density

Abstract Recent investigations of the electrode effect and the phenomenon of bubble electrification processes at the air-sea interface throw doubt on the applicability of using surface atmospheric electric observations made at sea by the Carnegie for proving the latitude effect in the columnar resistance of the atmosphere. Conduction current measurements were taken on flights during a period of decades by two instrumented aircraft in oceanic areas remote from sources of pollution. A composite of these measurements is given and confirms the notion that there is a latitude variation in air-Earth current. With the reasonable assumptions of an equal ionospheric potential and either low concentrations of Aitken nuclei or at least suitably small variations in their density with respect to latitude, the observed variation is apparently the integrated result of the Earths magnetic field acting on cosmic ray activity throughout the troposphere.

Measurements of the electrical characteristics of snowstorms

Abstract Two series of measurements were conducted in which ground-based apparatus and an instrumented NRL research aircraft were simultaneously employed to measure electrical phenomena associated with active snowstorms. Such measurements provided an opportunity to separate the effects of mechanically and electrically transported charge produced in the storm and an independent check on the data. Numerous effects were encountered which rendered the data collection difficult, but enough data were obtained to demonstrate agreement between ground and airborne measurements and to indicate the existence of a wide variety of electrical phenomena in snowstorms. The measurements yielded evidence of charged snowflakes of both polarities, pockets of charge within the snowclouds, and a wide range of total current fluxes to the earth.

Instrumentation for electrical measurements in snowstorms

Abstract Instrumentation was developed and subsequently used to study electric currents and their characteristics in snowstorms. Conduction current density was calculated from the product of atmospheric conductivity (measured by use of a Gerdien condenser) and electric field (measured by use of two new electric field meter designs of the radioactive potential probe type). Precipitation current was measured directly by two instruments, one averaging currents as a function of time and the other examining individual snowflakes and providing instantaneous precipitation information.