Niels Johan Føyn

Niels Johan Føyn (February 23, 1860 – June 13, 1945), original surname Nielsen, was a Norwegian meteorologist.

Føyn was born in Slagen in the municipality of Tønsberg, Norway. He was the son of the ship operator Peder Nielsen (1818–1904) and he later adopted the surname Føyn from the name of the farm where his family lived. and from 1915 to 1928 he was the deputy director of the Norwegian Meteorological Institute.

where Tm = monthly mean temperature, Tg = monthly mean of T1 (morning temperature) and T3 (evening temperature), k = constant, and T2 = midday temperature.

Selected works "Meteorologi" (Meteorology; as N. J. Nielsen, in Henrik Jæger (ed.), Illustreret norsk literaturhistorie, 1896) "Abhängigkeit des Barometerstandes von den Terrainverhältnissen" (Dependence of Barometer Readings on Terrain Conditions; in Meteorologische Zeitschrift, 1910) "Norges Klima" (Norway's Climate; in Norge 1814–1914, 1915) "Klima von Nordwesteuropa und den Inseln von Island bis Franz-Josef-Land" (The Climate of Northwest Europe and the Islands from Iceland to Franz Josef Land; coauthored with Bernt Johannes Birkeland, in Handbuch der Klimatologie, vol. 3, 1932)