The tropical cyclone is a solitary creature of the tropical oceans accompanied by violent rotating winds and torrential rain. Observational studies and diagnostic analyses leave little doubt that the energy required for driving the vortex comes from the latent heat of condensation released by tall convective clouds around the center, and that the frictionally induced inflow in the vortex plays a major role in supporting the continued activity of convective clouds. This dual character with respect to important scales of motion poses a great difficulty in investigating the dynamics of tropical cyclones as time-dependent phenomena. However, in order to understand the large-scale aspects of tropical cyclones, one may formulate the role of convective clouds in terms of cyclone-scale variables with only implicit consideration of the dynamics of individual clouds. The present study is an attempt to understand the basic mechanism of tropical cyclones by constructing a numerical-dynamical model on such a ... Abstract The tropical cyclone is a solitary creature of the tropical oceans accompanied by violent rotating winds and torrential rain. Observational studies and diagnostic analyses leave little doubt that the energy required for driving the vortex comes from the latent heat of condensation released by tall convective clouds around the center, and that the frictionally induced inflow in the vortex plays a major role in supporting the continued activity of convective clouds. This dual character with respect to important scales of motion poses a great difficulty in investigating the dynamics of tropical cyclones as time-dependent phenomena. However, in order to understand the large-scale aspects of tropical cyclones, one may formulate the role of convective clouds in terms of cyclone-scale variables with only implicit consideration of the dynamics of individual clouds. The present study is an attempt to understand the basic mechanism of tropical cyclones by constructing a numerical-dynamical model on such a ...