Аннотация:Popular picture of the interaction of the solar wind with the magnetosphere of the Earth considers the reconnection process as the dominant process leading to the plasma penetration inside the magnetosphere. Such explanations do not include the analysis of magnetopause stress balance. However, local destruction of such balance can be the source of magnetosheath plasma penetration inside the magnetosphere. Solar wind is the turbulent medium. Plasma density and velocity, interplanetary magnetic field constantly fluctuate. Such fluctuations are greatly increased near the magnetosphere in the magnetosheath region. The role of fluctuations of magnetic field in the magnetosheath in the formation of magnetospheric boundary layers is studied using data of high apogee satellites Themis, Interball and Geotail. It is shown that magnetosheath magnetic field fluctuations produce the real contribution to the stress balance on the magnetopause and can lead to plasma penetration inside the magnetosphere and magnetospheric boundary layer formation.