Miles Aylmer Fulton Barnett was born in Dunedin on 30 April 1901, the son of Louis Edward Barnett, a surgeon, and his wife, Mabel Violet Fulton. After attending Christ’s College, Christchurch, he went on to the University of Otago, where he gained the Beverly Scholarship in physics and higher mathematics (1921), the George Young Scholarship (1922), and a Senior Scholarship in mathematics. In 1924 he graduated MSc with double first-class honours in mathematics and physics. His thesis analysed the operation of some of the equipment used by Professor Robert Jack in his experimental radio broadcasts of 1921 and 1922.
Barnett entered Clare College, University of Cambridge, in 1924 to study in the Cavendish Laboratory. He was assigned by Sir Ernest Rutherford to an investigation of the propagation of radio waves under the supervision of E. V. Appleton. The existence of an electrically conducting layer in the upper atmosphere that could reflect radio waves beyond the curve of the earth had earlier been postulated by A. E. Kennelly in the United States and Oliver Heaviside in Britain. The experiments at Cambridge confirmed this theory, as well as showing that at times the reflections could come from a second, higher layer. These two ionised layers – the Kennelly–Heaviside and the higher Appleton–Barnett – are now known as the E and F layers respectively. For his study of radio propagation via the ionosphere Barnett was awarded a PhD in 1927 and elected a fellow of the Institute of Physics in 1929.
During 1927 Barnett took part in a scientific expedition to Greenland. On 19 October that year, in Cambridge, he married Margaret Alice Tenison Dalton. The couple returned to New Zealand, where Barnett became physicist at the Wellington head office of the newly established DSIR. Here he worked on a variety of problems connected with observatories, geophysical prospecting and refrigeration, and made seismological investigations of the Murchison and Hawke’s Bay earthquakes. He was appointed secretary, and later chairman, of the Radio Research Committee and a member of the Coverage Commission, which surveyed radio propagation conditions throughout the country.
While visiting England in 1935, Barnett was appointed to the New Zealand Meteorological Office (then a branch of the DSIR) to develop the services that would be needed for aviation. Before returning to New Zealand he gained his pilot’s licence under the tutelage of his younger brother, Denis, who later became an air chief marshal. Barnett spent the next few years recruiting and training staff and developing the facilities required by the fledgeling domestic aviation service. He was also involved in preparing for trans-ocean air services. Following the death of Edward Kidson in June 1939, Barnett was appointed director of the Meteorological Office (later the New Zealand Meteorological Service).
At the outbreak of the Second World War in September 1939, the Meteorological Office was transferred to the Air Department, and from February 1942 it was a uniformed branch of the Royal New Zealand Air Force. Barnett became a wing commander and at the height of the war had nearly 500 staff stationed from the equator to the subantarctic islands. He was made an OBE in 1945 and an officer of the US Legion of Merit in 1948. He was posted to the RNZAF Reserve of Officers in February 1947 with the rank of group captain, and to the Territorial Air Force from 1952 to 1962.
In the post-war period, observational networks were expanded, especially in the upper air, to service the new international air routes. These developments called for close collaboration between national meteorological services and led to the setting up of the World Meteorological Organisation. Barnett played an important part in drafting the structure of the new organisation and was New Zealand’s permanent representative from its inception in 1951 until 1962. He also held various other offices including membership of the executive committee from 1959 to 1962.
Although his work left him no time to continue his own research, Barnett offered encouragement to others and maintained an active interest in various scientific committees. In 1947 he was elected a fellow of the Royal Society of New Zealand. He served on the society’s council, and was president in 1964. He was also chairman of the national committee that organised New Zealand’s participation in the International Geophysical Year, and was a member of the Carter Observatory Board and the Dominion Museum management committee.
Miles Barnett retired from the Meteorological Service in July 1962. He died at Waikanae on 27 March 1979, survived by his wife, two daughters and a son. Throughout his distinguished career as a physicist and meteorologist he was highly regarded for his judgement, tact, quiet guidance and setting of high standards.