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Maxwell stress together with pressure variations associated with plasma density and temperature are responsible for maintaining the magnetospheric shape presented in Figure 2.2a, in equilibrium with the solar wind flow and its associated ram pressure. If this equilibrium is disturbed, for instance dayside and nightside reconnection cause erosion of the magnetopause and inward collapse of the magnetotail, respectively, then large‐scale magnetospheric flows are excited to rebalance the system. As described in section 2.2.1, in a steady state this causes a continuous circulation of the magnetospheric flux and plasma, and this magnetospheric convection is coupled to the ionosphere by tension forces and gives rise to ionospheric convection. Antisunward motions of open field lines and sunward motions of closed field lines give rise to the general twin‐cell convection pattern shown in Figure 2.1. The nature of this steady‐state flow and the associated electrodynamics are discussed in the following sections.