The Polarity Asymmetry of Sprite Producing Lightning: A Paradox Earle R. Williams MIT IAMAS Beijing, China August 2005 IAMAS 2 ERW Aug 05 Outline 3-way linkage: positive CGspriteQ-burst Global location of lightning C.T.R. Wilson idea for sprite initiation Polarity of ground flashes causal to sprites Why the overwhelming tendency for positive sprites? Global maps of energetic flashes Bimodal distributions of vertical charge moments Possible role of the duration of the moment change, and halos Asymmetry in slopes of current moment spectra Lightning responsible for gamma rays Conclusions IAMAS 3 ERW Aug 05 HR163-5 Sprite HR163-5 Lightning 3-Way Connection Positive Cloud-to-Ground Lightning (Spider Lightning) Sprites and Elves in the Mesosphere Transient Excitation of the Earth-Ionosphere Waveguide (Schumann Resonances) _P_1Y.ppt S A IAMAS 4 ERW Aug 05 Theory Used for Global Mapping IAMAS 5 ERW Aug 05 Sprite Initiation Following C.T.R. Wilson (1925) IAMAS 6 ERW Aug 05 General Results on the Polarity of Parent Lightning for Sprites Thousands of sprites caused by positive ground flashes Two well documented sprites caused by negative ground flashes (Barrington-Leigh et al, 1999) Estimate < 0.1% of sprites caused by ground flashes with negative polarity IAMAS 7 ERW Aug 05 Map Comparison for Positive and Negative Flashes IAMAS 8 ERW Aug 05 Global Map of Large Lightning Events from Rhode Island Station IAMAS 9 ERW Aug 05 Bipolar Distribution of Large Charge Moments IAMAS 10 ERW Aug 05 Percentage of All Lightning with Positive Polarity (Above Sprite Threshold) IAMAS 11 ERW Aug 05 Daytime Sprites Where on the globe are the sprites caused by supercritical negative charge moments? Hypothesis: In the daytime, when sprites cannot be seen IAMAS 12 ERW Aug 05 How Many of the Supercritical Events in the Daytime? (When Sprites Would Not Be Seen) IAMAS 13 ERW Aug 05 Oceanic Sprites Where are the sprites on the globe caused by supercritical negative charge moments? Hypothesis: Over the oceans where we lack observational coverage IAMAS 14 ERW Aug 05 World Color Map IAMAS 15 ERW Aug 05 Sprite-Capable Negative Lightning for Oceans IAMAS 16 ERW Aug 05 Sprite Halos What are the events caused by supercritical negative charge moments? Hypothesis: Halos caused by more-impulsive- than-usual negative ground flashes IAMAS 17 ERW Aug 05 Current Moment Spectra (I(f)dS) in Lower ELF Region Lightning current duration