THE FINE STRUCTURE OF THE ATMOSPHERIC FAIR WEATHER FIELD: An Investigation of Some Related Meteorological Factors

Journal/Book: Technical Report AP-23 Atmospheric Physics Program Navy Contract No. Nonr-710(22) August 1963. 1963;

Abstract: School of Physics University of Minnesota Minneapolis 14 Minnesota A summary of the fair weather electric field records made in Minnesota (Stuetzer 1963) has revealed a number of identifiable characteristics which if not unique to this midcontinent location at least have not been previously reported. It was found that during the daylight- hours under conditions of moderate to strong surface Winds several recognizable patterns of oscillation of the field occurred. These field oscillations were almost always greater at the city observing site in Minneapolis than at the site outside the city but the oscillations of largest scale occurred almost simultaneously at both locations. The longer period oscillation was s large scale decrease or even reversal of the electric field at the surface and was shown to be almost 180° out of phase with the daytime increase in Wind speed. The association with wind speed is very good and Stuetzer has suggested that the increased negative charge in the lower atmosphere implied by this observation could be produced by a process of separation and vertical transport of charge by dust particles carried aloft in the greater surface turbulence. (Freier 1960 has observed that similar atmospheric charging but more localized and intense occurs in a dust devil.) The second type of oscillation of the fair weather field with moderate to strong surface winds had a higher frequency and occurred with less regularity. On perhaps half of the observed days an oscillation appeared with an amplitude of about one third the normal fair weather field and a period that was judged to be about 10 minutes. (An example of a record exhibiting high frequency oscillations is shown in Figure 1.) It is these higher frequency oscillations with which this note is concerned. ... ___MH

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