Concept information
Preferred term
ionospheric E region
Definition(s)
- The E layer is the middle layer, 90 km (56 mi) to 150 km (93 mi) above the surface of the Earth. Ionization is due to soft X-ray (1–10 nm) and far ultraviolet (UV) solar radiation ionization of molecular oxygen (O₂). Normally, at oblique incidence, this layer can only reflect radio waves having frequencies lower than about 10 MHz and may contribute a bit to absorption on frequencies above. However, during intense sporadic E events, the Es layer can reflect frequencies up to 50 MHz and higher. The vertical structure of the E layer is primarily determined by the competing effects of ionization and recombination. At night the E layer weakens because the primary source of ionization is no longer present. After sunset an increase in the height of the E layer maximum increases the range to which radio waves can travel by reflection from the layer. (Wikipedia, The Free Encyclopedia, https://en.wikipedia.org/wiki/Ionosphere#E_layer)
Broader concept(s)
Synonym(s)
- E region
In other languages
-
French
URI
http://data.loterre.fr/ark:/67375/MDL-N7FBQFRB-2
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