  A magnetic flux tube may be considered both as a separate body and as a
confined field. As a field, it is affected both by differential rotation
($\Omega$-effect) and cyclonic convection ($\alpha$-effect). As a body, the
tube experiences not only a buoyant force, but also a dynamic pressure due to
downflows above the tube. These two competing dynamic effects are incorporated
into the $\alpha$-$\Omega$ dynamo equations through the total magnetic
turbulent diffusivity, leading to a flux tube dynamo operating in the
convection zone. We analyze and solve the extended dynamo equations in the
linear approximation by adopting the observed solar internal rotation and
assuming a downflow effect derived from numerical simulations of solar
convection zone. The model reproduces: the 22-year cycle period; the extended
butterfly diagram with the confinement of strong activity to low heliographic
latitudes $|\Phi|\le 35^\circ$; the evidence that at low latitudes the radial
field is in an approximately $\pi$ phase lag compared to the toroidal field at
the same latitude; the evidence that the poleward branch is in a $\pi/2$ phase
lag with respect to the equatorward branch; and the evidence that most of the
magnetic flux is present in an intermittent form, concentrated into strong flux
tubes.
