We propose a scenario to explain the observed phenomenon of amplitude alternation of adjacent 11-year solar activity cycles. It is shown that a noticeable radial gradient of angular velocity in the radiant zone (calculated by us on the basis of helioseismological experiments), acting on a weak relict radial magnetic field, generates a powerful deep toroidal magnetic field of constant direction (the deep Ω-effect of radiant zone). As a result of magnetic buoyancy, this field gradually penetrates from below to the turbulent layers of the SCZ, where the dynamo mechanism operates, responsible for the 11-year cyclical activity of the solar activity. Continuous "feeding" of the magnetic flux in the SCZ due to the additional toroidal flux emerging from below leads to variations in the power of the total toroidal field in adjacent cycles. The total toroidal field, rising on the solar surface, causes the observed alternation of the amplitude of adjacent solar 11-year activity cycles.
