This work presents a modified two-ray model unified with Uniform Theory of Diffraction (UTD) emphasizing the diffraction effects on a wedge and atmospheric effects. To validate the proposed formulation, a comparison between the modified two-ray model and the Split Step Parabolic Equation (SSPE) algorithm is made for a problem of a perfectly conducting wedge and standard atmosphere conditions at 2 GHz. The modified two-ray model showed similar behavior for pathloss results, compared to the SSPE numerical solution.