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Needle Propagation and Twinkling Characteristics
  • +16
  • Brian Hare,
  • Olaf Scholten,
  • Joseph R Dwyer,
  • C. Strepka,
  • S. Buitink,
  • A. Corstanje,
  • H. Falcke,
  • J.R. Horandel,
  • Tim Huege,
  • G. K Krampah,
  • P. Mitra,
  • K. Mulrey,
  • Anna Nelles,
  • Hershal Pandya,
  • Jörg P. Rachen,
  • S. thoudam,
  • T. N Trinh,
  • S. Veen,
  • Tobias Winchen
Brian Hare
University of Groningen

Corresponding Author:[email protected]

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Olaf Scholten
University of Groningen
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Joseph R Dwyer
University of New Hampshire
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C. Strepka
University of New Hampshire
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S. Buitink
Vrije Universiteit Brussels,
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A. Corstanje
Radbound University Nijmegen
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H. Falcke
IMAPP, Radboud University Nijmegen,
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J.R. Horandel
Radbound Universiteit Nijmegen
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Tim Huege
Karlsruhe Institute of Technology
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G. K Krampah
Vrije Universiteit Brussel
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P. Mitra
Vrije Universiteit Brussel
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K. Mulrey
Vrije University Brussels
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Anna Nelles
University of Erlangen
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Hershal Pandya
Vrije Universiteit Brussel
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Jörg P. Rachen
Vrije Universiteit Brussel
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T. N Trinh
Can Tho University
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S. Veen
ASTRON
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Tobias Winchen
Vrije Universeteit Brussels
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Abstract

Recently, a new lightning phenomena, termed needles, has been observed in both VHF and in optical along positive lightning leaders. They appear as small ($<$100 m) leader branches that undergo dielectric breakdown at regular intervals (called twinkles). Providing a coherent and consistent explanation for this phenomenon is challenging as each twinkle is a form of negative breakdown that propagates away from the positive leader. In this work we provide detailed observations of needles in VHF, observed during two lightning flashes. We show distributions of different needle properties, including twinkle propagation speeds, time between twinkles, and needle lengths, among others. We show a return stroke and multiple recoil leaders that quench needle activity. We also show that nearby needle activity does not seem to correlate together, and that needle twinkling can slow down by 10 to 30 percent per twinkle. We conclude by presenting possibilities for how the positive leader could induce negative propagation away from the positive channel, and we argue that twinkles can propagate like a stepped leader or like a recoil leader depending on the temperature of the needle, which implies that needle twinkles can probably propagate without emitting VHF.