ionosphere

1. The outer region of the Earth's atmosphere;
   Contains a high concentration of free electrons (synset 108606472)
   is a type of: part, region - the extended spatial location of something
   has:

   • d region, d-layer - the lowest region of the ionosphere (35 to 50 miles up) that reflects low-frequency radio waves
   • appleton layer, f layer, f region - the highest region of the ionosphere (from 90 to 600 miles up) which contains the highest concentration of free electrons and is most useful for long-range radio transmission
   • e layer, e region, heaviside layer, kennelly-heaviside layer - a region of the ionosphere (from 50 to 90 miles up) that reflects radio waves of medium length
   is a part of: air, atmosphere - the mass of air surrounding the Earth

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