Meeting‐at‐a‐Glance

s are listed chronologically, according to the conference schedule. Monday, 11 May 2009 intense to be observed from space. The underlying runaway process involves acceleration of electrons to relativistic energies in a strong thunderstorm electric Effects of Thunderstorms and Lightning in the Upper Atmosphere: An Overview field, followed by bremsstrahlung radiation via collisions with the neutral atmosphere. In addition to these processes, more recent work has indicated that lighting may also produce local x-rays and photonuclear effects, as well as inducing chemical effects in the upper atmosphere. [*D D Sentman*] (Geophysical Institute and Dept. of Physics, University of Alaska, Fairbanks, AK 99775 USA; ph. +1-907-474-6442; dsentman@gi.alaska.edu) The past twenty years have witnessed an explosion in the number of studies of previously unknown lightninginduced processes in the upper atmosphere that have significantly altered the traditional picture of the earth's electrical environment. Earlier balloon and rocket observations of electric fields and air conductivities above thunderstorms, and VLF observations of perturbations in the amplitudes and phases of the received signals from remote transmitters indicating lightning induced electron precipitation from the magnetosphere, had shown that thunderstorm electrical effects extended into the upper atmosphere, ionosphere and magnetosphere. There were, as well, observations of x-rays from in-cloud lightning that hinted at energetic electrical processes inside the thundercloud itself, and numerous anecdotal reports by pilots of mysterious flashes of light in the sky above thunderstorms. Overall, the picture of the global electrical environment was thought to be well understood, with the exception of a few unexplained anomalies. This talk will provide a broad overview of the subject matter of the Chapman Conference. It will briefly recount the key observations that have been made since 1989, indicate the context in which they were made and interpreted, and briefly discuss how they have extended the classical global electrical circuit picture to include fully kinetic descriptions of transient, non-LTE, energetic and chemical processes. Optical measurements will provide the focus for the talk, with supporting geophysical and laboratory observations included as needed. A few speculations are included about how this new understanding of the elements of the planetary electrical circuit could be applied to studies of similar classes of electrical processes in extraterrestrial environments. Spatial and Interannual Variability of Transient Luminous Event and Intense Lightning by ISUAL Experiment This picture changed dramatically in 1989 with the accidental observation of what was interpreted to be a large electrical discharge extending upward from the top of a thunderstorm. The discharge appeared to extend to what was, at the time, an incredible altitude of ~34 km, well above the tops of thunderstorms. Researchers quickly discovered that there are actually several different types of discharges that, in their totality, span the full distance from the troposphere to the ionosphere at ~90 km altitude. They include red sprites, blue jets, elves, sprite haloes, and gigantic jets, collectively termed Transient Luminous Events (TLEs). Instead of being rare or exceptional events, as was initially thought, they turned out to be common occurrences above most vigorous thunderstorm systems, satellite observations revealing the global occurrence rate of all types of TLEs to be ~2x10^6/yr. Theorists have identified the underlying processes as manifestations of conventional electrical breakdown or electron impact-excited fluorescence in an altitude region that was previously thought to be electrodynamically simple. Only a few years after the 1989 discovery of TLEs, an equally unexpected discovery was made, that thunderstorms also produce transient flashes of gamma rays sufficiently [*A B Chen*] (Institute of Space, Astrophysical and Plasma Sciences, National Cheng Kung University, Tainan, 70101, Taiwan; ph. 886-937099755; fax 88662096035, alfred@phys.ncku.edu.tw); Han-Tzong Su (National Cheng Kung University, Physics Department, Tainan 70101, Taiwan; ph. 886-6-2757575; htsu@energy.phys.ncku.edu.tw); Rue-Ron Hsu (National Cheng Kung University, Physics Department, Tainan 70101, Taiwan; ph. 886-6-2757575; rrhsu@energy.phys.ncku.edu.tw); C. L. Kuo (Institude of Space Science, National Central University, Jhongli, Taiwan; ph. 886-3-4227151-65777; fax 886-6-2096035; clkuo@jupiter.ss.ncu.edu.tw); Y. J. Lee (Department of Physics, National Cheng Kung University, Tainan, Taiwan; ph: 886.6.2757575-65212, fax: 886.6.2096035, yjlee@phys.ncku.edu.tw); L. Y. Tsai (Department of Physics, National Cheng Kung University, Tainan, Taiwan; ph. 886-6-2757575-65212; fax 886-6-2096035; esthertsay@gmail.com); J. K. Chou (Department of Physics, National Cheng Kung University, Tainan, Taiwan; ph. 886-6-2757575-65212; fax 886-6-2096035; jkchou@phys.ncku.edu.tw); L. J. Lee (Department of