British physicist. He/She was born in Bradford, and died in Edinburgh. In 1919 was Assistant of Rutherford at the Cavendish laboratory. He/She obtained a professorship at King's College of London in 1924 and 1936 in Cambridge. It became, in 1939, Secretary of State for scientific research and, subsequently, Vice-Rector of the University of Edinburgh. In 1901, Marconi had managed to transmit radio signals across the Atlantic; Kennelly and Heaviside explained after the fact by the existence of a layer or reflective layer in the atmosphere, composed of charged particles.
In 1925 Appleton demonstrated the existence of such receptor layer in the ionosphere. He/She transmitted signals by varying the frequency, and studying the signal received, showed that the interference occurred between the part of the signal that was traveling in a straight line from the transmitter to the receiver, and another part that was reflected by the ionosphere. Appleton measured the height of the reflective layer, estimating it at about 70 km. It was the first measurement of distances carried out with radio signals. This stratum is now known as the Heaviside layer or layer E.continuo with his studies and discovered a second layer on top of the first, called the Appleton layer or layer F. During the war he/she carried out the construction of the radar. He/She studied the emission of the milky way short waves and, in 1946, picked up an echo from the moon.For research in the field of the physics of the upper layers of the Earth's atmosphere, and the discovery of the ionized layer that bears his name, was awarded the Nobel Prize in Physics in 1947.