The effects of the basic current are considered. By means of the WKBJ method, the dispersion relation and the energy equation of the nonhomogeneous internal inertia-gravity wave are obtained.Case study of June 26, 1981 shows that the area of heavy rainfall corresponds to the possitive maximum of the wave energy and that the southern boundary of the rainbelt coincides with the zero line of mean vorticity for the layer between 1000hPa and 500hPa.