A three dimensional finite element solution of the parabolic equation for beam propagation in troposphere is newly formulated. The model represents propagation over a spherical earth and allows specification of frequency, polarization, beam width and antenna height. An efficient three dimensional form of the helmholtz equation with height dependant refractivity is used to model radio wave propagation in troposphere. By using this method, horizontal and vertical tropospheric characteristics are assigned to every element and different refractivity profiles can be entered at different stages. We also implement some abnormal environmental conditions to assess our method and investigate ducting phenomena in troposphere.