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Searching for intra-cloud positive leaders in VHF.

ABSTRACT: We have used the LOw-Frequency ARray (LOFAR) to search for the growing tip of an intra-cloud (IC) positive leader. Even with our most sensitive beamforming method, where we coherently add the signals of about 170 antenna pairs, we were not able to detect any emission from the tip. Instead, we put constraints on the emissivity of very-high frequency (VHF) radiation from the tip at 0.5 pJ/MHz at 60 MHz, integrated over 100 ns. The limit is independent on whether this emission is in the form of short pulses or continuously radiating. The non-observation of VHF radiation from intra-cloud positive leaders implies that they proceed in an extremely gradual process, which is in sharp contrast with the observations of other parts of a lightning discharge.

SUBMITTER: Scholten O

PROVIDER: S-EPMC10475077 | biostudies-literature | 2023 Sep

REPOSITORIES: biostudies-literature

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Searching for intra-cloud positive leaders in VHF.

Scholten O O Hare B M BM Dwyer J J Liu N N Sterpka C C Mulrey K K Veen S Ter ST

Scientific reports 20230902 1

We have used the LOw-Frequency ARray (LOFAR) to search for the growing tip of an intra-cloud (IC) positive leader. Even with our most sensitive beamforming method, where we coherently add the signals of about 170 antenna pairs, we were not able to detect any emission from the tip. Instead, we put constraints on the emissivity of very-high frequency (VHF) radiation from the tip at 0.5 pJ/MHz at 60 MHz, integrated over 100 ns. The limit is independent on whether this emission is in the form of sho ...[more]

PMID: 37660180

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