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E-LAYER [1 record]

Record 1 2004-03-19

English

Subject field(s)
  • Geophysics
  • Space Physics
DEF

Layer of the ionosphere exhibiting one or several maxima of electron density, at about 110 km.

CONT

The ionosphere is usually divided into two main layers: a lower layer, designated the E layer (sometimes called the Heaviside layer or Kennelly-Heaviside layer), which is between about 80 and 113 km (about 50 and 70 mi) above the Earth's surface and which reflects radio waves of low frequency; and a higher layer, the F layer (sometimes called the Appleton layer), which reflects higher-frequency radio waves.

CONT

The E layer exists in between the F and D layers, and forms only during daylight. Some radio refraction occurs in the E-layer at very high frequencies (VHF). This phenomenon is called Sporadic-E, because of its sporadic nature.

CONT

The Kennely-Heaviside Layer... or Heaviside Layer. ... is a layer of ionised gas occurring at 90-150 km in altitude ... It reflects medium-frequency radio waves, and because of this reflection radio waves can be propagated beyond the horizon. Propagation is affected by time of day, season, and sunspot activity. Its existence was announced in 1902 independently and almost simultaneously by the American electrical engineer Arthur Edwin Kennely? (1861-1949) and the British physicist Oliver Heaviside (1850-1925).

OBS

Heaviside layer: term officially approved by the International Civil Aviation Organization (ICAO).

Key term(s)
  • ionosphere E layer
  • ionosphere's E-layer
  • ionosphere's E layer
  • ionospheric E-layer
  • ionospheric E layer
  • E-layer of the ionosphere
  • E layer of the ionosphere
  • Kennelly-Heaviside layer
  • Kenelly-Heaviside Layer
  • Heaviside-Kennelly layer

French

Domaine(s)
  • Géophysique
  • Physique spatiale
DEF

Couche de l'ionosphère présentant un ou plusieurs maximums de densité électronique, située vers 110 km.

CONT

En 1902, l'ingénieur électricien américain Arthur Edwin Kennelly et le physicien britannique Oliver Heaviside (de façon indépendante et presque simultanément) annoncèrent l'existence probable d'une couche de gaz ionisés à haute altitude dans l'atmosphère, affectant la propagation des ondes radioélectriques. Cette couche, autrefois nommée couche de Heaviside, ou de Kennelly-Heaviside, est l'une des nombreuses couches constituant l'ionosphère. Bien que l'ionosphère soit transparente aux longueurs d'onde radio les plus courtes, elle réfracte ou réfléchit les longueurs d'onde plus importantes. Du fait de cette réflexion, les ondes radioélectriques peuvent se propager bien au-delà de l'horizon.

CONT

[...] le prochain niveau d'ionisation est appelé couche E. [...] Du fait que les électrons et les ions se recombinent assez rapidement ici, le niveau d'ionisation chute rapidement après le coucher du soleil. Bien qu'une petite quantité d'ionisation résiduelle persiste, la couche E disparaît pratiquement la nuit.

OBS

couche de Heaviside : terme uniformisé par l'Organisation de l'aviation civile internationale (OACI).

Key term(s)
  • couche de Kennelly-Heaviside
  • Couche Kenelly-Heaviside
  • couche Heaviside-Kennelly

Spanish

Campo(s) temático(s)
  • Geofísica
  • Física espacial
DEF

Capa de la ionosfera, situada a unos 110 km de altitud, con uno o varios máximos de densidad de electrones.

OBS

capa de Heaviside: término aceptado oficialmente por la Organización de Aviación Civil Internacional (OACI).

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