For most applications, simplified models may be used to describe the power spectra of quantities affected by atmospheric turbulence. The atmospheric model consists of a layered structure of wind velocity and turbulence strength, which is found to adequately approximate the usual measured data. Power spectra of such quantities as log-amplitude, phase, phase-difference, arrival angle, and arrival-angle difference, are derived for a single turbulence layer located at an arbitrary position along the path. The individual spectra are appropriately scaled and added together to form a composite spectrum. In one example, of the arrival-angle spectrum, we see that the high frequency asymptotic dependence is no fixed power-law, but may be almost anything, depending on the wind and turbulence distribution.