<P> The ionosphere (/ aɪ ˈɒnəˌsfɪər /) is a region of Earth's upper atmosphere, from about 60 km (37 mi) to 1,000 km (620 mi) altitude, that includes the thermosphere and parts of the mesosphere and exosphere . It is ionized by solar radiation, plays an important part in atmospheric electricity and forms the inner edge of the magnetosphere . It has practical importance because, among other functions, it influences radio propagation to distant places on the Earth . </P> <P> As early as 1839, the German mathematician and physicist Carl Friedrich Gauss postulated that an electrically conducting region of the atmosphere could account for observed variations of Earth's magnetic field . Sixty years later, Guglielmo Marconi received the first trans - Atlantic radio signal on December 12, 1901, in St. John's, Newfoundland (now in Canada) using a 152.4 m (500 ft) kite - supported antenna for reception . The transmitting station in Poldhu, Cornwall, used a spark - gap transmitter to produce a signal with a frequency of approximately 500 kHz and a power of 100 times more than any radio signal previously produced . The message received was three dits, the Morse code for the letter S. To reach Newfoundland the signal would have to bounce off the ionosphere twice . Dr. Jack Belrose has contested this, however, based on theoretical and experimental work . However, Marconi did achieve transatlantic wireless communications in Glace Bay, Nova Scotia, one year later . </P>

Where is the ionosphere located in the atmosphere