Vilhelm Bjerknes (1862-1951), a pioneer of modern meteorology, was especially known for his studies in hydrodynamics and thermodynamics and their relation to atmospheric motion. Following the steps of his father and even improving on his work, he devised a program of weather analysis and forecasting and founded the Geophysical Institute and Weather Service of Bergen.

Vilhelm Bjerknes was born on March 14, 1862, to Carl Anton Bjerknes, a respected mathematician and physicist, and Aletta Koren, a minister's daughter, in Kristiania (later renamed Oslo), Norway. Bjerknes' father was a devoted researcher of hydrodynamics. He had been a respected teacher of physics, but turned his focus towards the study of fluid-related movement, and also researched comparable studies in electro-dynamic phenomena. The younger Bjerknes was equally devoted to his father, and started working alongside him early in his scientific career. Although he assisted his father in his research, it was not long before he set out on his own to eclipse his father as a geophysicist.

Bjerknes began his formal education in mathematics and physics at the University of Kristiania in 1880. He studied hydrodynamics until 1887 when he started his M.S. degree. Upon completion of his degree, Bjerknes went to Paris on a state fellowship and began taking lectures by Jules Henri Poincare on electrical wave diffusion. It was then that he became acquainted with Heinrich Hertz's studies on the same subject.

In 1890, Bjerknes traveled to Bonn and attended the university there for two years. He was fortunate enough to become the assistant and first collaborator to Heinrich Hertz himself. Significant research during this period resulted in contributions in resonance and oscillatory circuit theory. Further research with resonance curve experiments also helped to validate Hertz's own theory and experiments. Wanting to return his focus to electrodynamics, Bjerknes returned to Norway in 1892 where he completed his Ph.D. Shortly thereafter, in 1893, he secured a lectureship at Stockholm's School of Engineering. His career further advanced when he procured a position as professor of applied mechanics and mathematical physics at the University of Stockholm in 1895. That same year he married Honoria Sophia Bonnevie, a Norwegian science student in Kristiania. Their son, Jacob Aall Bonnevie Bjerknes was born in 1897. Jacob was destined to not only follow in his father's footsteps in the study and discovery of meteorology, but to further his findings and expand on his father's knowledge. While the new family lived in Stockholm, Bjerknes ceased active research in electrodynamics and returned once more to his father's hydrodynamic studies. In 1902, he published Vorlesungenuber hydrodynamische Fernkrafte(1900-1902), a summary of his work in hydrodynamics.

Established Meteorology Foundations

By 1898, Bjerknes had combined personal mechanical research with a general analysis of the two primitive circulation theorems of absolute motion derived by British mathematician and physicist William Thomson Kelvin and German physicist Hermann Helmholtz. These two theorems dealt with velocities of circulation and the conservation of a circular vortex, which describes the remarkable stability of vortex motion. Applying his own changes to these theorems to the atmosphere and the ocean, the world's two biggest fluid systems, Bjerknes devised the theory of physical hydrodynamics. These were important finding as Bjerknes realized that atmospheric motion can be best understood when hydrodynamics and thermodynamics are combined. He knew that the heat of the sun is transformed into motion in our atmosphere. The friction of that atmospheric motion also generates heat, which is also turned into motion. Hence, thermodynamic laws are intertwined with fluid mechanics and this combination is necessary to fully understand the phenomena of the atmosphere.

Because motion in the atmosphere creates weather patterns, Bjerknes' findings entertained tremendous possibilities in meteorological forecasting. Until then, forecasting was unreliable at best, even though certain progressions of weather systems were observable and understood and important in that forecasting. Long-term outlooks were particularly difficult. Bjerknes' discoveries, however, presented a more structured atmospheric dynamic that enabled meteorologists to forecast more predictably and accurately, especially in the longer term. These offerings were based on a detailed three-dimensional analysis of atmospheric conditions. According to Arnt Eliassen, "He put forward the view that weather forecasting should be dealt with as an initial value problem of mathematical physics and carried out by numerical or graphical integration of the governing equations. This is nothing more than treating the atmosphere as a physical system, but at the time it was a revolutionary idea."

Bjerknes knew his findings were paramount to weather forecasting and realized that economic support was necessary to both continue and share his research. In 1905, he traveled to the United States to present his program of lectures at the Massachusetts Institute of Technology and to seek funding for continued study. He shared his vision for forecasting and was enthusiastically received. He received a research associateship and was awarded a yearly grant from the Carnegie Institute in Washington, D.C. This was continued until the U.S went to war in 1941. Eliassen explained, "The money could hardly have found a better use; it enabled Vilhelm to employ and educate a considerable number of research assistants, all of whom became well-known geophysicists." It was certainly the case, for Bjerknes was an ideal collaborative partner for younger students, as his history of assistants and their future histories would prove.

Bjerknes moved, in 1907, to the University of Kristiania, where he served as professor of applied mechanics and mathematical physics. In 1909, he began a series of lectures that called for an awareness of the importance of new techniques in the science world as they related to weather forecasting and atmospheric understanding. He wrote and published the first volume of Dynamic Meteorology and Hydrography, that dealt with the fixed state of the atmosphere and fluids, with his new assistant, Johann Wilhelm Sandstrom. Bjerknes published a second volume the next year with his new assistants Theodor Hesselberg and Olav M. Devik. This substantial work dealt with massless movement of fluids and the atmosphere. The third and final volume would not be published until 1951, and was written by Bjerknes' collaborators. In 1911, another collaborator arrived to join his work, Harald Ulrik Sverdrup, a fellow Norwegian who would become an important polymathic geophysicist. German scientists were impressed with Bjerknes' work and, in 1912, they offered him a professorship and a position as director of the new geophysics institute at the University of Leipzig. This recognition made Bjerknes' geophysical work more visible.

At the start of his stay at the German university, research was successful. Bjerknes had brought along T. Hesselberg and H.U. Sverdrup, who worked with him in addition to the several German research assistants and students. When World War I broke out, however, he lost many of his student assistants to war service. He also lost Hesselberg and Sverdrup, which left him in serious need for assistants. His son, Jacob, left his studies in Kristiania to join his father, along with Halvor Solberg. Even with reinforcements to assist, the war made research and living more difficult in Leipzig. About this time, a zoologist and Arctic explorer, Fridtjof Nansen, and oceanographer, Bjorn Helland-Hansen, offered him the opportunity to establish his own geophysical institute at the new University of Bergen. Bjerknes accepted. This would prove to be the most productive season of his career.

Founded the Weather Service of Bergen

Bjerknes and his assistants, including his son Jacob, began immediately with their research programs at the new Weather Service. He started research in the dynamic theory of atmospheric movement, systematic daily observation of the basic meteorological conditions, intensive calculation of predictions and graphic representation of meteorological change, and timely weather forecasts.

By the end of the war it was increasingly clear that Bjerknes' work would be indispensable. The Norwegian government set up a weather observation network based on Bjerknes' applications in response to the need. By July 1918, while the new techniques were still experimental, the Western Bergen Weather Service began reporting daily for the government and military. Once the usefulness of the service was more widely recognized, increasingly refined forecasts became accessible to farmers, fisherman, and the newly developing aviation business.

Besides the growing public need and enthusiasm for the dissemination of forecasts, Bjerknes' team welcomed other major research advances. The group's work resulted in the polar front theory, the theory of motion in cyclone systems, and the elaborate upper front theory. These were all major advances of the time and greatly advanced the science of modern meteorology. Jacob, or Jack as he became known, was instrumental in the developments during this time. Building on the research of his father, he recognized that the air masses named by his father had their own cycle. In a paper, "On the Structure of Moving Cyclones" written in the fall of 1918, he stated that "warm air ascends along the sloping frontal surfaces, causing bands of clouds and precipitation to form along the fronts, whereas the cold air sinks and spreads out along the ground." He also noted that "these vertical motions represent a reduction of the potential energy, which could account for the formation of the cyclone's kinetic energy." Bjerknes also continued to publish abundantly. His crowning achievement, On the Dynamics of the Circular Vortex with Applications to the Atmosphere and to Atmospheric Vortex and Wave Motion, was released in 1921. Another, Physical Hydrodynamics, a work completed with Jacob, Solberg, and Bergeron, was published in 1933. The many collaborators and assistants Bjerknes was fortunate to have with him enthusiastically disseminated the Bergen meteorological approach when they, in their turn, left the team and spread out in different countries, including the United States.

Bjerknes accepted a position as professor of mechanics and mathematical physics at the University of Oslo, and left the Geophysical Institute of Bergen to Sverdrup, his son Jacob, and other collaborators he had trained. At the University of Oslo he taught theoretical physics and hoped to write a series of texts on that subject. In 1929, he published his first book on vector analysis and kinematics. In addition, he returned to his father's studies and looked into his hydro-magnetic theories. He was unable, however, to resolve the problems with his father's theories.

In addition to his myriad research efforts, he was a powerful spokesman for the theoretical and practical side of meteorology. He remained so even after he retired from the University of Oslo in 1932, at the age of 70. His son, Jacob, continued in the research footsteps of his father grandfather, and furthered the study of modern meteorology. Bjerknes died of heart failure in Oslo, Norway on April 9, 1951

The result of 100 years of research done collectively by Carl, Vilhelm, and Jacob Bjerknes has helped to transform meteorology from a science of random observation to that of data collection and weather forecasting based on physical and mathematical principles.

Further Reading

• Friedman, Robert Marc, Appropriating the Weather: Vilhelm Bjerknes and the Construction of a Modern Meteorology, Cornell University Press, 1989.
• Notable Twentieth-Century Scientists, Gale Research, 1995.
• World of Scientific Discovery, 2nd. ed., Gale Group, 1999.
• "Bjerknes, Vilhelm Frimann Koren," http://www.encyclopedia.com/printable/01521.html (11/10/99).
• Eliassen, Arnt. "Jacob Aall Bonnevie Bjerknes," http://www.nap.edu/readingroom/books/biomems/jbjerknes.html (11/2/99).