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D-LAYER IONOSPHERE [1 record]

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Alphabetical list of terms

Record 1 2004-03-19

English

Subject field(s)
  • Atmospheric Physics
  • Geophysics
  • Space Physics
DEF

Layer, existing only by day, which constitutes the lower part of the ionosphere; it begins at about 70 km and merges with the lower part of the E layer.

CONT

The D layer is the closest layer to the Earth's surface, and also forms only during daylight hours. This layer is a layer which instead of refracting signals to Earth, absorbs them. The D layer absorbs high frequency and medium frequency radio signals. In fact, sometimes, D layer absorption can grow so great that all radio communications by way of the ionosphere are wiped out for a short period.

OBS

This region of the ionosphere is situated in between 50 and 90 kilometers, below the E layer.

Key term(s)
  • D-layer of the ionosphere
  • ionosphere's D layer
  • ionosphere D-layer
  • ionosphere D layer
  • ionospheric D-layer
  • ionospheric D layer

French

Domaine(s)
  • Physique de l'atmosphère
  • Géophysique
  • Physique spatiale
DEF

Couche, existant seulement de jour, qui constitue la partie inférieure de l'ionosphère ; elle débute vers 70 km d'altitude et se fond avec la partie inférieure de la couche E.

CONT

Lors d'une activité solaire intense, certaines transmissions radio sont tellement perturbées qu'elles entraînent parfois un véritable «black-out» des communications. Dans le cas d'une éruption solaire, c'est la brusque augmentation de la concentration électronique dans la couche D qui provoque une atténuation tellement forte de l'intensité des ondes radio de courte longueur d'onde (10 à 100 m), que la réception de celles-ci devient inaudible. Par contre, les ondes de grandes longueurs d'onde sont réfléchies à un niveau plus bas de la couche D.

Spanish

Campo(s) temático(s)
  • Física de la atmósfera
  • Geofísica
  • Física espacial
DEF

Capa presente sólo de día y que comprende la parte inferior de la ionosfera.

OBS

Comienza a unos 70 km y en su parte superior se confunde con la parte inferior de la capa E.

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