Niels Johan Føyn

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

Niels Johan Føyn
Born	Niels Johan Nielsen (1860-02-23)February 23, 1860 Slagen, Tønsberg, Norway
Died	June 13, 1945(1945-06-13) (aged 85)
Nationality	Norwegian
Occupation	Meteorologist

Føyn was born in Slagen in the municipality of Tønsberg, Norway.^[1][2] He was the son of the ship operator Peder Nielsen (1818–1904) and he later adopted the surname Føyn from the oeconym of the farm where his family lived.^[2] He received his candidatus realium degree in 1886 and then worked as an assistant at the Norwegian Meteorological Institute.^[1] He received a state scholarship to study in Berlin and Vienna from 1893 to 1895.^[1] From 1903 to 1915, Føyn was the supervisor of the Bergen Meteorological Observatory,^[3] and from 1915 to 1928 he was the deputy director of the Norwegian Meteorological Institute.^[1] He was made a member of the Norwegian Academy of Science and Letters in 1904.^[1]

Legacy

In meteorology, a Köppen-like formula known as Føyn's formula is used for calculating monthly mean temperatures:^[4][5]

T_m = T_g + k(T₂ − T_g)

where T_m = monthly mean temperature, T_g = monthly mean of T₁ (morning temperature) and T₃ (evening temperature), k = constant, and T₂ = midday temperature.^[6]

Selected works

• "Meteorologi" (Meteorology; as N. J. Nielsen, in Henrik Jæger (ed.), Illustreret norsk literaturhistorie, 1896)^[2]
• Wolken-Beobachtungen inn Norwegen 1896–97 (Cloud Observations in Norway 1896–97; 1900)^[1][7]
• "Abhängigkeit des Barometerstandes von den Terrainverhältnissen" (Dependence of Barometer Readings on Terrain Conditions; in Meteorologische Zeitschrift, 1910)^[1]
• "Das Klima von Bergen, I. Niederschläge" (The Climate Of Bergen. Part 1: Precipitation; in Bergens Museums aarbok, 1910), "II. Lufttemperatur" (Part 2: Air Temperature; ibid., 1916)^[1][8]
• "Norges Klima" (Norway's Climate; in Norge 1814–1914, 1915)^[1]
• "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)

References

1. Blangstrup, Christian (1920). Salmonsens Konversationsleksikon, vol. 9. Copenhagen: J. H. Schultz Forlagsboghandel. p. 293. Retrieved December 2, 2018.
2. Steenstrup, Hjalmar (1934). Hvem er hvem. Oslo: H. Aschehoug & Co. Retrieved December 2, 2018.
3. Bergens Museums aarbog. Bergen. 1905. p. 97.{{cite book}}: CS1 maint: location missing publisher (link)
4. Nordli, Øyvind; Tveito, Ole Einar (2008). Calculation of Monthly Mean Temperature by Köppen's Formula in the Norwegian Station Network (PDF). Oslo: Norwegian Meteorological Institute. p. 9. Retrieved December 2, 2018.
5. Birkeland, Bernt Johannes (1936). "Mittel und Extreme der Lufttemperatur". Geofysiske Publikasjoner. 14 (1).
6. Gjelten, Herdis M.; Nordli, Øyvind; Grimenes, Arne A.; Lundstad, Elin (2014). "The Ås Temperature Series in Southern Norway–Homogeneity Testing and Climate Analysis". Bulletin of Geography – Physical Geography Series. 7: 10. doi:10.2478/bgeo-2014-0001. S2CID 52026933. Retrieved December 2, 2018.
7. Fortschritte der Physik. Braunschweig: F. Vieweg und Sohn. 1902. p. 325.
8. "Meteorologiske forhold". Statistiske Oversikter 1948. Oslo: Statistisk sentralbyrå: 16. 1948.