A Beautiful Diagram of Cyclone Activity (1922)

JF Ptak Science Books  Post 2750

This lovely and significant piece of sci-art appeared in Jacob Bjerknes and H. Solberg's  "Life Cycle of Cyclones and the Polar Front Theory of Atmospheric Circulation"¹ in 1922. This was an expansion of an earlier paper of 1919², and provided the basis for the motion of the atmosphere in terms of warm and cold fronts. “Although rapid transitions or discontinuities in temperature, pressure, and wind velocity had been noted in Jacob’s first model—and even by nineteenth century meteorologists—and although such discontinuities had been theoretically postulated, the 1919 Bergen cyclone model represented the introduction of discontinuities into meteorology as the major focus for practice and, eventually, theory. These “fronts,” as they later were termed, were endowed with scientific reality through the introduction of major changes in forecasting practice. The cyclone model based on fronts entailed the ability to specify in time and three-dimensional space important weather phenomena associated with cyclones to a much greater degree than earlier models could achieve. During the next few years the Bergen group of Vilhelm and Jacob Bjerknes, Ernst Calwagen, Halvor Solberg, and Tor Bergeron, among others, expanded this preliminary cyclone model and accompanying forecasting methods to a comprehensive system for explaining midlatitude weather changes. The polar front, the occlusion process, an evolving cyclone model, and air mass analysis were the conceptual foundation for a new era in meteorology.”³

 

The two authors “...pictured the polar front as a string of families of cyclones, described by dashed lines linking successive warm and cold front”.--Mark Monmonier, Air Apparent: How Meteorologists Learned to Map, Predict, and Dramatize Weather, pg 64, with several reproductions of some of the lovely diagrams.

Notes:

1. J. Bjerknes and H. Solberg, Life Cycle of Cyclones and the Polar Front Theory of Atmospheric Circulation. Offprint/separate, Geofysiske Publikationer 3, no. 1, 1922. 12x9, 18pp (paginated 1-18). Bound in cloth, with a half-title and title, though no publication data save for a running abbreviation of the journal name and volume above the text. Nicely bound in buckram. Provenance: U.S. Navy, Naval War College. “Polar front theory is attributed to Jacob Bjerknes, derived from a coastal network of observation sites in Norway during World War I. ... The convergence line ahead of the low became known as either the steering line or the warm front. The trailing convergence zone was referred to as the squall line or cold front.”--Wiki
2. This was evidently a longer and more thorough version of a paper submitted by Bjernkes and Solberg to the Monthly Weather Review in 1919 on the findings of the Bergen group. --Robert Marc Friedman, Appropriating the Weather: Vilhelm Bjerknes and the Construction of a Modern Meteorology, p. 180; also noting that this article is “frequently cited”.
3. Complete Dictionary of Scientific Biography.
4. Wikipedia entry for Bjerknes. 

“Bjerknes was part of a group of meteorologists led by his father, Vilhelm Bjerknes, at the University of Leipzig. (“Bjerknes's father, Vilhelm. has often been called the father of modern meteorology. This title is doubly appropriate, for not only did Vilhelm’s vision and research programs lead to establishing new directions, methods, and the conceptual foundation for the science, but Vilhelm’s son also played a fundamental role in creating this new era in atmospheric science.”) Together they developed the model that explains the generation, intensification and ultimate decay (the life cycle) of mid-latitude cyclones, introducing the idea of fronts, that is, sharply defined boundaries between air masses. This concept is known as the Norwegian cyclone model.”--Wikipedia

“The "Bergen School of Meteorology" is a school of thought which is the basis for much of modern weather forecasting. Founded by the meteorologist Prof. Vilhelm Bjerknes and his younger colleagues in 1917, the Bergen School attempts to define the motion of the atmosphere by means of the mathematics of interactions between hydro- and thermodynamics, some of which had originally been discovered or explained by Bjerknes himself, thus making mathematical predictions regarding the weather possible by systematic data analysis. Much of the work was done at the Geophysical Institute, University of Bergen, in Bergen, Norway.”--Wikipedia  It should be noted that Jacob was the chief forecaster and head at Bergen 1918-1931.--Complete Dictionary of Scientific Biography