Experimental evidence of nonlinear influence of solar activity on the earth atmosphere and environment

Study of the tree-ring growth along the northern timber-line at: Kola penin sula and in Finland in the Past demonstrated the existence of cyclic oscill ations of the tree-ring width. The cycles obtained correlate with the funda mental periods of solar activity (about 90 and 23 years) and with the perio ds which are related to combinative frequences (about 18 and 33 years) of m entioned fundamental frequences. It means that the influence of the solar v ariability on the terrestrial environment and climate has a nonlinear natur e.