@prefix mdl: <http://data.loterre.fr/ark:/67375/MDL> .
@prefix skos: <http://www.w3.org/2004/02/skos/core#> .
@prefix dc: <http://purl.org/dc/terms/> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .

mdl:-K97RVF06-G
  skos:hiddenLabel "ondes siffleuses"@fr, "whistler waves"@en, "Onde siffleuses"@fr, "Onde siffleuse"@fr, "whistlers"@en, "sifflements"@fr, "Whistler wave"@en ;
  skos:altLabel "sifflement"@fr, "whistler"@en ;
  skos:definition "A whistler is a very low frequency (VLF) electromagnetic (radio) wave generated by lightning. Frequencies of terrestrial whistlers are 1 kHz to 30 kHz, with a maximum amplitude usually at 3 kHz to 5 kHz. Although they are electromagnetic waves, they occur at audio frequencies, and can be converted to audio using a suitable receiver. They are produced by lightning strikes (mostly intracloud and return-path) where the impulse travels along the Earth's magnetic field lines from one hemisphere to the other. They undergo dispersion of several kHz due to the slower velocity of the lower frequencies through the plasma environments of the ionosphere and magnetosphere. Thus they are perceived as a descending tone which can last for a few seconds. The study of whistlers categorizes them into Pure Note, Diffuse, 2-Hop, and Echo Train types. (Wikipedia, The Free Encyclopedia, <a href=\"https://en.wikipedia.org/wiki/Whistler_(radio)\" target=\"_blank\">https://en.wikipedia.org/wiki/Whistler_(radio)</a>)"@en, "Le mode sifflement est un mode de propagation dispersif dans les plasmas magnétisés. Excitées par les parasites atmosphériques créés par la foudre, des perturbations se propagent dans la magnétosphère d'un hémisphère à l'autre de la Terre. Son caractère dispersif provoque un étalement des fréquences. L'enregistrement du signal transposé en signal acoustique donne l'impression d'un sifflement. Ce sifflement caractéristique est dénommé \"siffleur\" (issu de \"whistler\" en anglais). (Wikipedia, L'Encylopédie Libre, <a href=\"https://fr.wikipedia.org/wiki/Mode_sifflement\" target=\"_blank\">https://fr.wikipedia.org/wiki/Mode_sifflement</a>)"@fr ;
  skos:related mdl:-T42J56L4-Q, mdl:-M97SDCN5-B ;
  skos:prefLabel "onde siffleuse"@fr, "whistler wave"@en ;
  skos:exactMatch <https://en.wikipedia.org/wiki/Whistler_(radio)>, <https://fr.wikipedia.org/wiki/Mode_sifflement> ;
  dc:modified "2022-09-28"^^xsd:date ;
  skos:inScheme mdl: ;
  a skos:Concept ;
  skos:broader mdl:-N2JTH5BP-5 .

mdl:-N2JTH5BP-5
  skos:prefLabel "onde radioélectrique"@fr, "radio wave"@en ;
  a skos:Concept ;
  skos:narrower mdl:-K97RVF06-G .

mdl:-T42J56L4-Q
  skos:prefLabel "foudre"@fr, "lightning"@en ;
  a skos:Concept ;
  skos:related mdl:-K97RVF06-G .

mdl:-M97SDCN5-B
  skos:prefLabel "very low frequency"@en, "très basse fréquence"@fr ;
  a skos:Concept ;
  skos:related mdl:-K97RVF06-G .

mdl: a skos:ConceptScheme .