#atmosphere  the mass of air surrounding the Earth; "there was great heat as the comet entered the atmosphere"
  supertype:  #region.location__part  the extended spatial location of something; "the farming regions of France"; "religions in all parts of the world"; "regions of outer space"
  subtype:  #airspace  the atmosphere above a nation and deemed to be under its jurisdiction
  part of:  #Earth.terrestrial_planet
  part:  #ionosphere  the outer region of the Earth's atmosphere; contains a high concentration of free electrons
     part:  #D-layer__D_region  the lowest region of the ionosphere (35 to 50 miles up) that reflects low-frequency radio waves
     part:  #Appleton_layer__F_layer__F_region  the highest region of the ionosphere (from 90 to 600 miles up) that contains the highest concentration of free electrons and is most useful for long-range radio transmission
     part:  #Kennelly-Heaviside_layer__Heaviside_layer__E_layer__E_region  a region of the ionosphere (from 50 to 90 miles up) that reflects radio waves of medium length

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