Meaning of D layer

D layer

Pronunciation: [key]
  1. the lowest region of the ionosphere, characterized by mounting electron and ion density: exists, during the day only, from about 43 to 50 mi. (70 to 80 km) altitude. Cf. D region.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.
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