Аннотация:The results from analysis of nonzonal disturbances of the field of geopotential at the 30 hPa level (m = 1, 2, 3) are presented. A long-period modulation of the amplitude of harmonics is revealed. Eigenfunctions and eigenvalues of the Laplace tidal equation (σ = 0, m = 1) are calculated for an actual latitudinal wind profile. It is shown that the observed first zonal harmonic is attributed to the same mode (m = 1, n = 2) during different years. It is concluded that the difference between wave amplitudes cannot be explained by the difference in the stratospheric zonal circulation during different years but is connected with processes in the troposphere.