Vilhelm Bjerknes was a Norwegian meteorologist and physicist who made significant contributions to the understanding of atmospheric and ocean dynamics.
Vilhelm Bjerknes is known for his work in the development of weather forecasting.
He was born on 14 March 1862 in the city of Christiania (later Kristiania, since 1925 Oslo). He studied science at the University of Kristiania and received his master's degree in 1888 and his doctorate in 1892. In the meantime, he went to Paris in 1889 and followed Poincare's lectures on electrodynamics, and then worked with Hertz in Bonn for two years. After becoming a professor of applied mechanics and mathematical physics at Stockholm University in 1895, he was influenced by the hydrodynamic research of his father, Carl Anton Bjerknes (1825-1903), professor of physics and mathematics at Kristiania University, and turned his attention to the field. By applying the laws of hydrodynamics and thermodynamics to the motions of the atmosphere, he became the pioneer of dynamic meteorology and scientific methods of weather forecasting. Returning to Norway in 1907 and teaching applied mechanics and mathematical physics at Kristiania University until 1912, Vilhelm Bjerknes became professor of geophysics at the University of Leipzig between 1912-1917 and the director of the Leipzig Institute of Geophysics, which was established by his suggestion. While he was teaching at Bergen University in Norway between 1917-1926, he founded the Bergen Geophysics Institute, was a professor at the University of Oslo between 1926-1932, and died on April 9, 1951, in Oslo.
His son, Jacob Aall Bonnevie Bjerknes, was born in Stockholm on November 2, 1897, two years after they accepted the invitation of Stockholm University and settled in Sweden. Even as a child, he adopted his father's field of interest and participated in almost all of his studies. Equipping Norway with a network of meteorological observation stations during World War I, the Bjerknes developed the concept of air masses in 1919, evaluating the results of several years of observation and basing atmospheric motions on the foundations of fluid dynamics. Jacob Bjerknes, who was appointed director of the Weather Prediction Center in Bergen in 1920, completed his doctorate at the University of Kristiania in 1924 and became a professor of meteorology at the University of Bergen in 1930. Ten years later, he settled in the USA and assumed the post of professor of meteorology at the University of California until his death, he became a citizen of the USA in 1946 and died on July 7, 1975, in Los Angeles.
Vilhelm Bjerknes started from the basic laws of hydrodynamics and thermodynamics in order to explain the movements of the ocean and atmosphere. After explaining that the ocean currents are due to the pressure difference between water masses of different temperatures and densities, he attributed the reason for the atmospheric movements to the conversion of this heat into mechanical energy by the air masses that are heated by the heat emitted from the Sun. As a result of their joint work, the Bjerknes identified four distinct air masses, two cold (arctic and polar) and two warm (tropical and equatorial) air masses that dominate different geographical latitudes of the northern hemisphere. They named the boundary lines separating these air masses at different latitudes, developing at different latitudes, as "fronts" with the effect of the ongoing World War I. Explaining the formation and movements of cyclones and anticyclones with the emergence of these fronts, the Bjerknes laid the foundations for long-term weather forecasts and contemporary meteorology by mapping the places where the air masses were interrupted and the fronts.