It is expected that hot gas emanates hydrodynamically from the sur face of an accretion disk in the gravitational field of a central object through internal heating or irradiation. We examine such disk winds under a simple approximation in which the force balances parallel and perpendicular to the streamlines are decoupled. The angular momentum is assumed to be con served along each streamline. The energy is injected into each streamline at the flow base on the surface of the disk. Under these approximations, we reveal the properties of a two-dimensional flow pattern, such as the transonic surfaces, of disk winds. When the temperature distribution at the wind base is not so steep (flatter than lire, re being the equatorial dis tance), the gas of the inner disk is gravitationally bound near the disk to form a corona, while the gas on the outer disk is unbound to escape infinity, passing through the critical points. On the other hand, if the temperature distribution is steeper than lire, the gas on the inner disk is unbound and that on the outer disk is bound. When it is lire, the gas is free or bound all over the disk surface. Although the transonic nature, such as the loca tion or number of the critical points, depends naively on the configuration of streamlines, the global behavior is independent of the streamlines and shows the characteristic properties of hydrodynamical winds from the disk.