Turbulence in the atmosphere is a phenomena affecting the transport and diffusion of trace gases. The theory and physical mechanisms that produce turbulence in the atmosphere are not understood well. Turbulence cannot be measured directly, but can be estimated using some instruments which can measure atmospheric parameters in high spatial and temporal resolutions. MST radar is a useful tool for estimating turbulence. Estimation of turbulence using MST radar involves a lot of assumptions. There are various methods to estimate turbulence using MST radar. Three separate, distinctly different methods are the the power method, doppler spectral width method, and variance method. All the methods have their own strengths and weaknesses. A new approach for the variance method for the estimation of the turbulence is presented and is compared with that obtained by other methods. Possible mechanisms for the generation of turbulence, and the conditions for isotropic and anisotropic turbulence are discussed.