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F layer definition

F layer

the two dense layers of ions in the F region of the ionosphere that are used to reflect long-range radio signals: the F layer, at an altitude of c. 200 to 300 km (c. 125 to 185 miles), exists during the day, and the permanent F layer, or Appleton layer, is at c. 225 to 400 km (c. 140 to 250 miles)

Webster's New World College Dictionary Copyright © 2009 by Wiley Publishing, Inc., Cleveland, Ohio.
Used by arrangement with John Wiley & Sons, Inc.

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