Abstract: The effect of heat supplied by the ocean on the development of large scale disturbances is investigated. With the aid of two empirical formulas, the heating due to seasurface evaporation and the turbulent exchange of heat with the ocean surface for 12 selected cases of weather process in winter is computed. These cases include 11 processes(about 60 days) over the North Pacific Ocean and one process over the North Atlantic Ocean. In the first part of this paper, the relation of the phase difference between the heating field and the large scale disturbances to the development of the disturbance is investigated. In Section 5 & 6, the contributions of the heating on the 500-1000 MB thickness tendency and on the change of the 500 MB vorticity is analyzed in some selected cases.