Function: noun
Date: 1930
: the lowest part of the ionosphere occurring approximately between 30 and 55 miles (50 and 90 kilometers) above the surface of the earth
Function: noun
Date: 1930
: the lowest part of the ionosphere occurring approximately between 30 and 55 miles (50 and 90 kilometers) above the surface of the earth
Merriam Webster Collegiate English Dictionary. Merriam Webster - Энциклопедический словарь английского языка. 2012