D layer Hear it!

D layer definition

D layer

the lowest area of the ionosphere, having increased ion density and existing only in the daytime: it begins at an altitude of about 70 km (c. 43 mi) and merges with the E layer

Webster's New World College Dictionary Copyright © 2005 by Wiley Publishing, Inc., Cleveland, Ohio.
Used by arrangement with John Wiley & Sons, Inc.

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