Electron tubes provided the very environments in which the natural environment became accessible to measurement and high-speed computation. The following paper offers some avenues into the peculiar moment in the mid-twentieth century when the open space of the planetary was technologically operationalized in closed and controlled interiors. The 1945-56 Electronic Computer Project at the Institute for Advanced Study in Princeton, NJ works like a magnifying glass for tracing this momentous epistemic liaison. It reveals the specific circumstances in which the parallel development of a fully electronic calculating machine and the first digital-numerical models of the atmosphere took place. The paper revisits the co-development of post-war computing and post-war geophysics, in which tubes functioned as the material joints, essentially providing the condition of possibility for calculating the large-scale flows of air over the globe. It moreover highlights the role of tubes as a sensory medium, i.e. as an instrument that literally transforms material chemical elements and their subspecies (isotopes) into electric signals, and thereby into quantifyable data about planet Earth. Mass spectrometry emerged concurrently with electronic computing and is based on the same physics lab and electrical engineering culture of tube design as the latter. In essence, gas discharge tubes coupled with electrometer tubes were to produce some of the very signals that were then processed by calculating tubes: a closed techno-epistemic loop that represents a fundamentally new mode of processing the quantified properties of the real since around 1950.