**Vilhelm Bjerknes** was a Norwegian physicist and meteorologist important in the development of weather forecasting.

- Vilhelm wrote his first paper New hydrodynamic investigations in 1882 when he was only 20 years old.
- The city was named Christiania when Vilhelm was born there, became Kristiania in 1877, then was renamed Oslo in 1925.
- Throughout Vilhelm Bjerknes's life he was associated with this city with its three different names and all three names appear in this biography.
- In 1888 Vilhelm was awarded his Master's Degree from the University of Kristiania after studying mathematics and physics.
- By this time Carl Bjerknes had become a recluse and continuing the collaboration would have led, Vilhelm believed, to his own scientific isolation.
- After graduating from Kristiania, Bjerknes was awarded a state scholarship which allowed him to study abroad.
- This was not a short trip, for Bjerknes spent two years from 1890 to 1892 in Bonn.
- Together Hertz and Bjerknes studied electrical resonance which proved important in the development of radio.
- Bjerknes was appointed as a lecturer at the Högskola (School of Engineering) in Stockholm in 1893 then, two years later, he became professor of applied mechanics and mathematical physics at the University of Stockholm.
- Important for the future direction of Bjerknes's research was the fact that he now applied the generalisation of the theory of vortices of Thomson and Helmholtz, which he had studied, to motions in the atmosphere and the ocean.
- Bjerknes began to work out a research plan that he would use hydrodynamics and thermodynamics so that, given a particular state of the atmosphere, he would be able to compute its future state.
- Their son, Jacob Bjerknes, was born on 2 November 1897.
- In 1905 Vilhelm Bjerknes visited the United States, described some of the fundamental steps he had already taken in the theory of air masses, and explained his plans to apply mathematics to weather forecasting.
- Bjerknes accepted the chair of applied mechanics and mathematical physics at the University of Kristiania in 1907.
- In 1912 Bjerknes was offered the chair of geophysics at the University of Leipzig, and also the directorship of the new Leipzig Geophysical Institute which was just being founded.
- Jacob and Vilhelm Bjerknes collaborated in establishing a network of weather stations in Norway and it was data gathered from these weather stations which led to their theory of polar fronts.
- In 1917 Bjerknes was offered a chair at the University of Bergen and he was given the opportunity to found the Bergen Geophysical Institute.
- Despite being 55 years old when he moved to Bergen, most historians agree that Bjerknes did his best work there.
- Vilhelm Bjerknes and his associates at Bergen succeeded in devising equations relating the measurable components of weather, but their complexity precluded the rapid solutions needed for forecasting.
- The next step forward in the mathematical approach was due to Richardson in 1922 when he reduced the complicated equations produced by Bjerknes's Bergen School to long series of simple arithmetic operations.
- There were two scientists from whom Bjerknes had the greatest admiration.
- Bjerknes had visited Heaviside in 1919 in Torquay, England.
- By that time Heaviside was living a lonely life in hard financial circumstances and Bjerknes did his best to assist him.
- In 1923 Bjerknes published a collection of papers on electrical resonance, and wrote an introduction dedicating them to the memory of Hertz.
- Bjerknes made his final move in 1926 when he accepted the chair of applied mechanics and mathematical physics at the University of Oslo (Kristiania had been renamed Oslo in 1925).
- During his years at the University of Oslo until his retirement in 1932 Bjerknes put a considerable effort into teaching.
- As indicated in the above quote, Bjerknes remained active after his retirement.
- Although Bjerknes was 84 years old in 1946, he made the trip to the Newton Tercentenery Celebrations in England.
- The honours which Bjerknes was awarded are far too numerous to list here, but we mention a few.

Born 14 March 1862, Christiania (now Oslo), Norway. Died 9 April 1951, Oslo, Norway.

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Analysis, Origin Norway

**O’Connor, John J; Robertson, Edmund F**: MacTutor History of Mathematics Archive