Method for simulating the convective cell and other global atmospheric motions. A shallow layer of water in a round vessel is heated at the edge, to represent the equator, and cooled at the centre, to represent the polar region. As the dish-pan is rotated, various motions are produced in response to the radial temperature gradient and to the speed of rotation. At lower speeds, the flow pattern is zonal, but with faster rotation large waves develop and incorporate closed circulations. See also hadley cell; rossby wave.