Appleton, Edward Victor (1892-1965)

British physicist. He worked at Cambridge under Ernest Rutherford from 1920. He proved the existence of the Kennelly-Heaviside layer (now called the E-layer) in the atmosphere, and the Appleton layer beyond it, and was involved in the initial work on the atom bomb. He was awarded the Nobel Prize for Physics in 1947 for his work on the physics of the upper atmosphere. He was made KCB in 1941 and GBE in 1946.

Appleton was born in Bradford, West Yorkshire, and educated at Cambridge. He became interested in radio as signals officer during World War I, and his research into the atmosphere was of fundamental importance to the development of radio communications. He was professor at King's College, London 1924-36, and at Cambridge 1936-39. He was secretary of the Department of Scientific and Industrial Research 1939-49, and principal and vice chancellor of Edinburgh University 1949-65.

By periodically varying the frequency of the British Broadcasting Corporation (BBC) transmitter at Bournemouth and measuring the intensity of the received transmission 100 km/62 mi away, Appleton found that there was a regular fading in and fading out of the signals at night but that this effect diminished considerably at dawn as the Kennelly-Heaviside layer broke up. Radio waves continued to be reflected by the atmosphere during the day but by a higher-level ionized layer. By 1926 this layer, which Appleton measured at about 230 km/145 mi above the Earth's surface (the first distance measurement made by means of radio), became generally known as the Appleton layer (it is now also known as the F-layer).