That portion of the ionosphere existing approximately 50 to 95 km above the surface of the Earth. ( 188 ) Note: Attenuation of radio waves, caused by ionospheric free-electron density generated by solar radiation, is pronounced during daylight hours. Because solar radiation is not present at night, ionization ceases, and hence attenuation of radio waves ceases.
D REGION
Meaning of D REGION in English
Telecommunication standard terms English vocab. Английский словарь стандартных телекоммуникационных терминов. 2012