Hurricanes in a Tank? Large-Scale Convective Organization and Cyclonic Flow Under Moderate Rotation in Laboratory Tank Experiments

Rotating tank experiments have long been a cornerstone of geophysical and astrophysical fluid dynamics research. However, experimental studies often focus on conditions far removed from the large-scale aggregation of convection seen in Earth’s tropical and subtropical latitudes, such as tropical cyclones, mesoscale convective complexes, and heat lows. These atmospheric phenomena involve relatively slow rotation, asymmetric buoyancy sources between the surface and the atmosphere, and broad spatial scales. Our study investigates these dynamics using simple tank experiments where a shallow layer of hot water cools to the air above, bounded by insulating walls and a flat bottom. The experiments reveal distinct flow regimes depending on the convective Rossby number (Ro C ), a dimensionless ratio of rotational to convective time scales. Large, persistent cyclonic vortices emerge for Ro C greater than about 1, while weaker, short-lived cyclonic flows and anticyclonic flows occur for values below 1. These results, confirmed through analyses of flow persistence and spatial organization, highlight the role of slow rotation, asymmetric heat fluxes, and boundary conditions in generating large-scale circulations that couple with organized convection. These experiments illustrate how simple, single-phase setups can illuminate the basic physics of tropical-cyclone formation and convective aggregation, and motivate complementary laboratory and numerical work.