Flows of air, flows of electrons

Today’s comprehension of the global climate and other elements of the Earth system is synonymous with the computation of their dynamic processes in digital machinery. Given their central role in assessing the criticality of the planetary- and epoch-scale changes currently underway, it seems crucial to fathom this conceptual and material basis of the Earth (system) sciences. This is what the field of historical epistemology has to offer. It explains how certain forms and formattings of knowledge came to be (and why others did not) by helping to understand the historical path dependencies, relationships, limits, and possibilities that frame a particular way of knowing. How then and under what circumstances became geophysical phenomena and their time-based evolution represented by digital and electronic media? This paper seeks to contribute to this historical analysis by revisiting the emergence of atmospheric motion modeling until the middle of the 20th century. It argues that the close association between atmospheric flows and electron currents was not just merely a practical consideration but one that rested on longer traditions in which fluid and electromagnetic phenomena intimately shared epistemic and technological contexts as well as formulas. Highlighting the electrophysical context from which Vilhelm Bjerknes derived his famous circulation theorem, that, in turn, led to the rise of modern atmospheric science, the paper attempts to make the theoretical and practical proximity, if not sometimes community, of hydrodynamics and electrodynamics more palpable and legible. The essay describes and interprets a long-standing and quite productive back-and-forth relationship between these two seemingly different physics-based realms, in which experimental electrophysics informed theoretical geophysics and electronics opened up ways for numerical experiments on fluid motions.