  Magnetic activity is a global property of the Sun; the complex processes of
solar activity are connected with the solar magnetic fields. For solar-type
stars and the Sun magnetic activity depends on the physical parameters of the
star. In this article we study the relationships between the duration of
activity cycle and effective temperature for solar-type stars and the Sun.
We've tried to explain these relationships due to the existence of layer of
laminar convection near the bottom of the convective zone of the star. In this
layer the Rossby waves are formed. They generate the primary poloidal magnetic
field, which is the source of energy of the complex phenomena of magnetic
activity.
