Environmental conditions for hurricane formation in the experiment of the rotation period of 40 Earth days and surface temperature shown in Fig. 3a. (a) Long-term mean vertical velocity at 500 hPa (shading) and winds at 300 hPa (vector); (b) planetary vorticity; (c) relative vorticity at 850 hPa; (d) relative humidity at 600 hPa; (e) potential intensity; (f) vertical wind shear between 300 and 850 hPa.