Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
OVERVIEW AND RECOMMENDATIONS 20 tion, ground-based and balloonborne measurements have indicated that there is a global electrical response to cosmic-ray and solar variations that is also not understood. The bulk electrical properties of the middle atmosphere are poorly defined, and there is a need to determine the ion composition and chemistry both for quiet conditions and during solar-terrestrial events. There is also new evidence that the electric fields produced by thunderstorms and lightning can produce significant disturbances in the electrical structure of the upper atmosphere and magnetosphere. The horizontal electric fields that are generated by the ionospheric-wind dynamo and the solar-wind/ magnetospheric dynamo propagate downward to the Earth's surface where they can locally perturb the fair-weather electric field by about 1-2 percent and 20-50 percent, respectively. Horizontal currents in the middle atmosphere and the characteristics of the equalization layer need to be determined in order to understand better the electrical interactions that occur between the upper and lower atmosphere. To determine (1) the electrical properties of the middle atmosphere, (2) the effects of thunderstorms on ionospheric and magnetospheric processes, and (3) the effects of time variations in the cosmic-ray and energetic solar- particle fluxes on the properties of the global circuit, additional measurements are required. Theoretical investigations and modeling are also important components of such investigations. Lightning has long been known to be a source of whistlers in the Earth's magnetosphere, and recent spacecraft observations suggest that lightning also generates whistler-mode signals on Jupiter. The questions of just how lightning fields couple to a whistler duct and whether these fields have effects on the ionosphere or magnetosphere are important and need further investigation. References Dolezalek, H., and R. Reiter, eds. (1977). Electrical Processes in Atmospheres , Steinkopff, Darmstadt, Germany. Kessler, E., ed. (1982). Thunderstorms: A Social, Scientific, and Technological Documentary , Univ. of Oklahoma Press, Norman, Okla. Orville, R. E. , ed. ( 1985 ). Proceedings of the VIIth International Atmospheric Electricity Conference, special issue of J. Geophys. Res. 90 (June 30, 1985). Volland, H., ed. (1982). Handbook of Atmospherics, Vol. I and II, CRC Press, Inc., Boca Raton, Fla.
