## Das Problem der wettervorhersage, betrachtet vom Standpunkte der Mechanik und der Physik in Meteorologische Zeitschrift 21 No. 1 pp. 1-7, January 1904 [ORIGINAL WRAPPERS IN CUSTOM CASE]

Wien: Ed. Hölzel, 1904. 1st Edition. Original wrappers (quite rare in this form) and housed in custom clamshell case. FIRST EDITION OF BJERKNES'S SEMINAL MATHEMATICAL MODEL OF ATMOSPHERIC DYNAMICS, now known as "the primitive equations of weather" – the mechanics and physics of weather. Bjerknes proposed these equations in the paper offered here, and in so doing, pioneered numerical weather forecasting, which is based on applying physical laws to the atmosphere and solving mathematical equations associated with these laws. [Note that we also offer this item in its bound, full volume form].

Vilhelm 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 large-scale 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 mid-latitude weather systems (low pressure systems)" (Earth Observatory, NASA).

"In a programmatic paper published in 1904, Bjerknes proposed the procedure now known as numerical weather prediction" (ibid). "Bjerknes argued that atmospheric physics had advanced sufficiently to allow weather to be forecast using calculations. He developed a set of equations whose solution would, in principle, predict large-scale atmospheric motions" (Sloan, Before 1955: Numerical Models). Bjerknes's equations include: Boyle's law; Charles' law; the continuity equation; the Navier-Stokes equations of motion; the thermodynamic equation; and the water continuity equation. "Bjerknes proposed a "graphical calculus," based on weather maps, for solving the equations." (ibid).

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" (EO). "Since equations govern how meteorological variables change with time, if we know the initial condition of the atmosphere, we can solve the equations to obtain new values of those variables at a later time (i.e., make a forecast)" (Numerical Weather Predicition). 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" (EO). Item #1335

CONDITION: 4to. The wrappers remain well and solidly attached. The front wrapper is toned with a small nick at the outer margin. Internally the journal is bright, clean, and in fine condition. The clamshell case is pristine, gilt-ruled on the front board and at the spine.

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Price:
$1,300.00
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