by Steve Graham • August 14, 2000 Vilhelm Bjerknes is considered by many to be one of the founders of modern meteorology and weather forecasting. Born on March 14, 1862, in the Norwegian town of Christiania, Bjerknes was destined for a career in science. As a young boy, Bjerknes assisted his father, Carl Bjerknes (a professor of mathematics at the University of Christiania), in carrying out experiments to verify the theoretical predictions that resulted from his father's hydrodynamic research. He continued this collaboration during his undergraduate studies at the University of Kristiania in 1880 (the city was renamed Kristiania in 1877). After studying mathematics and physics, Bjerknes received his Master's Degree from Kristiania in 1888. During this time, he decided to cut all collaborative ties with his father, as he showed an increasing tendency toward professional isolation and a fear of publishing the results of his research. Young Vilhelm believed that continuing work with his father would be detrimental to his career, a tough decision for a son who was devoted to his father. Soon after graduation, Bjerknes was awarded a state scholarship that enabled him to continue his studies abroad. Arriving in Paris in 1889, he attended lectures on electrodynamics given by Jules Henri Poincare. Then, in 1890, he moved to Bonn, Germany, and became an assistant to, and eventually a scientific collaborator with, the German physicist Heinrich Hertz. Together, Hertz and Bjerknes conducted a comprehensive study of electrical resonance (an effect in which the resistance to the flow of an electrical current becomes very small over a narrow frequency range) that was influential in the development of radio. In 1892, Bjerknes returned to Norway and completed his doctoral thesis on the work that he did in Bonn. 
On the Shoulders of Giants

After two years as a lecturer at the Hogskola (School of Engineering) in Stockholm, Bjerknes became a professor of applied mechanics and mathematical physics at the University of Stockholm in 1895. Two years later he discovered the circulation theorems that led him to a synthesis of hydrodynamics and thermodynamics applicable to largescale motions in the atmosphere and oceans. He then began devising a research plan that would use these theorems to compute the future state of the atmosphere given its present (initial) condition. This work ultimately resulted in the theory of air masses and fronts. As a primary piece of the modern weather forecasting puzzle, this theory described the life cycle of midlatitude weather systems (low pressure systems). On November 2, 1897, Bjerknes' son Jacob was born. Jacob would later collaborate with his father and become a famous meteorologist in his own right, discovering the mechanism that controls the behavior of midlatitude cyclones. In a programmatic paper published in 1904, Bjerknes proposed the procedure now known as numerical weather prediction. He suggested that weather prognosis (forecasting) should be considered as an initial value problem of mathematical physics, and could be carried out by integrating the governing equations forward in time, starting from the observed, initial state of the atmosphere. In short, Bjerknes discovered that with enough information about the current state of the atmosphere, scientists can use math formulas to predict future weather patterns. Unfortunately, due to the lack of processing facilities (computers), the calculations he envisioned were not feasible at that time. Nevertheless, Bjerknes considered weather forecasting as the principal objective of meteorological research, trusting that adequate observations and computer facilities would emerge in the future. In 1905, during a trip to the United States, Bjerknes presented his research on the theory of how air masses move and explained his plans to apply mathematics to weather forecasting. The Carnegie Institution was so impressed they awarded him a grant to pursue his research interests. He would continue to receive their support until 1941. After chairing the Department of Applied Mechanics and Mathematical Physics at the University of Kristiania for five years, Bjerknes accepted the chair of geophysics at the University of Leipzig (Germany), and the directorship of the new Leipzig Geophysical Institute in 1912. He was joined by many of his Kristiania colleagues, as well as his son Jacob, who also became a collaborator during his time at Leipzig. Together, father and son established a network of weather observing stations in Norway. The data gathered from these stations would eventually lead to the development of their theory of polar fronts. next: Continuing the Saga

On the Shoulders of Giants

In 1917, Bjerknes accepted a position with the museum in Bergen (Norway; now part of the University of Bergen), where he founded the Bergen Geophysical Institute. Bjerknes was 55 years old at the time and most historians agree this is where Bjerknes did his best work, continuing his research into the mathematical approach to weather forecasting. Working with his son Jacob and Jacob's fellow student Halvor Solberg, they were later joined by the Swedish meteorologist Tor Bergeron. Together, this extraordinary group of meteorologists put forward the theory that weather activity is concentrated in relatively narrow zones, which form the boundaries between warm and cold air masses. They called these zones "fronts," an analogy with the First World War battlefronts. The theory was widely acclaimed and became known as the "polar front theory of a developing wave cyclone" or, simply, the "polar front theory." What these scientists gave to the world was a working model of how a midlatitude cyclone progresses through the stages of birth, growth, and decay. Their model marked a turning point in atmospheric science. While at the Institute, in 1921, Bjerknes published "On the Dynamics of the Circular Vortex with Applications to the Atmosphere and to Atmospheric Vortex and Wave Motion." Now considered a classic, this work offered one of the first modern and extensive accounts of the structure and evolution of cyclones. This work remarkably remains unaltered to this day. Bjerknes made his final move in 1926 when he accepted the chair of the Department of Applied Mechanics and Mathematical Physics at the University of Oslo (Kristiania was renamed Oslo in 1925). There, in addition to his meteorological studies, he continued to study the hydrodynamical work started by his father. In 1926, he also produced the theory that sunspots are the erupting ends of magnetic vortices broken by the different rotation rates of the sun's poles (slower rotation) and equator (faster rotation). During his years at the University of Oslo, Bjerknes attracted and inspired gifted students, by putting forth considerable effort into his teaching practices. He also published a book on vector analysis (mathematical treatments of physics concepts such as velocity, acceleration, and force) in 1929 that was produced as the first volume of a larger textbook on theoretical physics. next: Links and References

On the Shoulders of Giants

Internet References "Bjerknes, Vilhelm Friman Koren," Encyclopedia Britannica Online
O'Connor, J.J., and E.F. Robertson, July 2000: "Vilhelm Frimann Koren Bjerknes." School of Mathematics and Statistics. University of St. Andrews, Scotland. European Geophysical Society. "Vilhelm Bjerknes." [Online] URL: http://www.copernicus.org/EGS/egs_info/bjerknes.htm Print References Ahrens, C. Donald. Meteorology: An Introduction to Weather, Climate, and the Environment. St. Paul: West Publishing Company, 1994. Friedman, Robert Marc. Appropriating the Weather: Vilhelm Bjerknes and Construction of a Modern Meteorology. Cornell University Press, 1989. Moran, Joseph M., and Michael D. Morgan. Meteorology: The Atmosphere and the Science of Weather. Upper Saddle River: Prentice Hall, 1997. Schneider, Stephen H., ed. Encyclopedia of Climate and Weather. New York: Oxford University Press, 1996. return to: Vilhelm Bjerknes

On the Shoulders of Giants

Weather Simulation: Thunderstorms  