Abstract: The turbulence spectrum and intermittency problem concerning light propagation in the atmosphere are addressed. The validity and limitation of current turbulence spectrum models are discussed, and roles of turbulence characteristic scales are analyzed. A experimentally tested model for temperature structure functions in fully developed turbulence is developed. The model can be used for the construction of the random phase screen in the numerical simulation of light propagation in order to study the effect of turbulence intermittency on light propagation.