simple terms scintillation is changing of light from bright light to dim light in a given period of time. Atmospheric scintillation is the changing of light intensities in time and space at the plane of a receiver that is detecting a signal from a transmitter located at a distance. The received signal at the detector fluctuates as a result of the thermally induced changes in the index of refraction of the air along the transmit path. These index changes cause the atmosphere to act like a series of small lenses that deflect portions of the light beam into and out of the transmit path. The time scale of these fluctuations is of the order of milliseconds, approximately equal to the time that it takes a volume of air the size of the beam to move across the path, and therefore is related to the wind speed. Scintillation can change by more than an order of magnitude during the course of a day, being the worst, or most scintillated, during midday when the temperature is the highest.