Toward Better Understanding of Sprite Streamers: Initiation, Morphology, and Polarity Asymmetry

International audienceThe goal of this tutorial talk is to provide an introduction to physics of gas discharges as relevant to interpretation of morphological features observed in large scale electrical discharges termed sprites and sprite halos that are produced at mesospheric and lower ionospheric altitudes in the Earth's atmosphere by lightning. We will introduce parameters typically used for quantitative description of electron avalanches and discuss importance of space charge effects on different spatial scales, including sprite halos (exhibiting 10s of km transverse extents) and sprite streamers (requiring sub-meter resolution for accurate description). The special emphasis will be placed on interpretation of initiation and development of sprite streamers observed in high-speed video observations and critical review of the most recent modeling efforts related to these observations