Function: noun
Date: 1933
: a layer of the ionosphere occurring about 65 miles (110 kilometers) above the earth's surface during daylight hours that is capable of reflecting shortwave frequencies
Function: noun
Date: 1933
: a layer of the ionosphere occurring about 65 miles (110 kilometers) above the earth's surface during daylight hours that is capable of reflecting shortwave frequencies
Merriam Webster Collegiate English Dictionary. Merriam Webster - Энциклопедический словарь английского языка. 2012