Abstract: The general expressions of the correlation and spectrum functions between turbulent velocities and/or velocity-gradients for isotropic turbulence are derived. The odd-even nature of spectrum functions with regard to space frequency is analysed. Some confusing problems about atmospheric turbulence concerning the current literature and specifications of flying qualities are discussed and clarified. Finally, an example of the aircraft response in longitudinal motion to atmospheric turbulence is presented, and some conclusions of significance are drawn from this example.

Key words: atmospheric turbulence, turbulence spectrum, aircraft response