barotropic

baro- + -tropic ◆In meteorological use introduced, along with baroclinic, by the Norwegian physicist and meteorologist Vilhelm Bjerknes (1862-1951) in “On the Dynamics of the Circular Vortex with Applications to the Atmosphere and Atmospheric Vortex and Wave Motions,” Geofysiske Publikationer (published by the Norwegian Geophysical Commission), vol. 2, no. 4 (1921), pp. 2-3. The term barotropic (originally in Dutch as barotropisch) had been used earlier in the laboratory of the Dutch physicist Heike Kamerlingh Onnes in reference to an experiment involving helium-rich vapor and liquid hydrogen: at increasing pressure the helium sank to the bottom of the hydrogen, an effect characterized as “the barotropic phenomenon” (see H. Kamerlingh Onnes and W.H. Keesom, “Bijdragen tot de kennis van het ψ-vlak van van der Waals. XII. Over het zinken der gasphase in de vloeistofphase bij binaire mengsels,” Koninklijke Akademie van Wetenschappen te Amsterdam (Royal Netherlands Academy of Sciences), Verslag van de Gewone Vergaderingen der Wis- en Natuurkundige Afdeeling van 26 Dec. 1906 tot 26 Apr. 1907, deel XV, 2de gedeelte, pp. 507-13).