We give some results of measurements of the r. m. s. value of the solar limb motion amplitude for different phases of the partial solar eclipse in morning hours. It is found that the process of active destruction of the inversion layer by uprise convective flows occurs at the illuminance E > 0.2E₀, where E₀ is the illuminance from the Sun in zenith. Before this moment, the relationship between the motion amplitude σ and zenith distance of the Sun z corresponds to the theoretical law σ(z) = σ(0)√(sec(z)).