Sketch of the flows and their correlation with the magnetic field that lead to Joy’s law. In the first phase, the toroidal field is pushed through the surface by a radial upflow (upper panel). This creates radial field at the surface. Associated with the upflow is a horizontal outflow (middle panel), which advects the newly emerged magnetic bipoles, which further enhances the loss of toroidal field. The horizontally diverging material is acted on by the Coriolis force, so that the flows become helical. In particular, the U_ϕ flow drives a flow in the north-south direction, U_θ, as shown in the lower panel. This north-south flow moves the preceding polarity toward the pole and the leading polarity towards the equator. The time evolution of the magnetic fields imply an electric fields E^FE associated with the flux emergence. The corresponding contribution of flux emergence to the electromotive force is discussed in the text.