Alan Thorpe enjoys a hymn to some of the founders of the science and institutions of weather forecasting.
Inventing Atmospheric Science: Bjerknes, Rossby, Wexler, and the Foundations of Modern Meteorology
- James Rodger Fleming
It is thanks to the efforts of an international community of meteorologists and atmospheric scientists that accurate forecasts of major weather systems can be made reliably up to about a week ahead (see P. Bauer et al. Nature 525, 47–55; 2015). Many researchers contributed to the revolution in weather sciences in the first half of the twentieth century, so it is perhaps invidious to single out a few.
Science historian James Fleming focuses on three: Norwegian Vilhelm Bjerknes, Swede Carl-Gustaf Rossby and American Harry Wexler. The first two I expected; the third I was intrigued to learn more about. Fleming devotes about 60 pages to each man's life and work, and mentions many others and their impacts, mostly on US weather forecasting.
To the cognoscenti, the essentials of Bjerknes's and Rossby's science will be familiar. Fleming's fascinating account clarifies why these two were giants of leadership. Bjerknes created the 'Bergen school' of meteorology, which used rigorous scientific principles to understand and predict the evolution of weather features such as fronts and cyclones. The school included his son Jacob among many talented, mainly Scandinavian, scientists. Rossby established university schools of meteorology in Stockholm and Chicago, and at the Massachusetts Institute of Technology in Cambridge. The breadth of Wexler's role emerges through his contributions to the development of techniques and operational weather forecasting, particularly in the United States.
Between the birth of Bjerknes — the oldest — in 1862 and the death of Wexler, the youngest, in 1962, there passed a formative and innovative century. As Fleming reveals, their lives were linked, with Bjerknes teaching Rossby and Rossby, Wexler.
In 1904, in 'Weather forecasting as a problem in mechanics and physics', Bjerknes set the agenda for applying the laws of physics to the atmosphere to predict the weather (V. Bjerknes Meteorol. Z. 21, 1–7; 1904). His vision was to use a sufficiently accurate knowledge of the state of the atmosphere and the laws that govern its evolution to forewarn people about weather to come. His motivation was to make his mark in what was for him a new field of science — he began his career working with his father, a physicist at the University of Oslo, on fluid analogies for the electromagnetic field. He was eager, too, to provide practical advice on hazards that affected mariners, farmers and the public.
Fleming notes the absence of a book-length biography of Rossby, and I hope that this will be rectified soon. To me, he is a first among equals. As well as building institutions, he established important principles, such as the conservation of potential vorticity — used to understand the development of rotation in cyclones and other weather systems — and the large-scale atmospheric wave patterns named after him. He was a leader in developing techniques such as experiments that simulate the atmosphere in a rotating tank of water, as well as aircraft soundings and the use of radiosondes, or radio-based measurements using weather balloons. A polymath with a high public profile, he was pictured on the cover of Time magazine in December 1956, with the title “Weatherman”.
Wexler's contributions include making the first research flight into a hurricane, using radar to track storm systems, working towards space observations and developing the use of computers in meteorology.
From the findings of these three men, Fleming expertly weaves a tapestry of broader developments, from early uses of computers and satellites to numerical predictions with supercomputers. He explores intentional weather modification, radioactive fallout, rocketry, air pollution and electromagnetism. For example, the air movements made apparent when researchers tracked the fallout from nuclear-bomb tests in the 1950s provided insight into atmospheric circulation.
The penultimate chapter covers what Fleming calls the birth of atmospheric science in the late 1950s, coinciding with planning for the International Geophysical Year in 1957–58. In 1956, Rossby proposed enlarging the definition of meteorology to include elements such as atmospheric chemistry and relevant biological processes. Much of what we regard as contemporary developments, such as the understanding of atmospheric composition or geoengineering, were in the minds of 1950s researchers, Fleming points out.
Modifying the reflectivity of the planet to avoid harmful climate change was discussed by Wexler and others as early as 1958. In a 1962 speech, Wexler said: “We are in weather control now whether we know it or not.” Fleming also focuses on the importance of committees in planning developments such as the creation of the US National Center for Atmospheric Research in 1960, and the role of top researchers in leading these committees.
A historical account has to have boundaries, and Fleming barely hints at what came after 1960. I found the discussion of Edward Lorenz's work on chaos that led to aspects of probabilistic forecasting disproportionately brief.
What shines through Inventing Atmospheric Science is the commitment of three men to applications of research to society, and their desire to advance our understanding of weather. This is an inspirational story, very well told.
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Thorpe, A. Meteorology: The brainstormers. Nature 532, 30–31 (2016). https://doi.org/10.1038/532030a