Scintillometry is a ground-based horizontal remote-sensing technique for measuring several aspects of atmospheric turbulence. Varying from essentially turbulence parameters such as the structure parameter of the refractive index or the inner scale length of turbulence up to mass- and energy-balance fluxes such as momentum and sensible heat, scintillometers deliver highly precise and spatial information to its users.
Most people know scintillation through the twinkling of stars or the deformation of distant objects over hot asphalt resulting from a heat haze. In the atmosphere, hot and cool air parcels act like small lenses that bend the light. Vigorous mixing of these air parcels by turbulence makes that light coming from the object is scattered continuously, so that the sight of the object becomes distorted. Essentially, scintillometry is based on this principle. Light coming from a constant light source at the transmitter is scattered by the turbulence, whereas the remaining part reaches the receiver at some distance away. Thus, fluctuations in the measured light intensity directly relate to the strength of the turbulence, even if we cannot always see it with the naked eye.