Abstract: A system and method detect turbulence in a fluid by processing image data to isolate and detect fluctuations in a frequency range indicative of turbulence. By making use of a Fourier or other frequency transformation to convert a set of time-dependent intensity data into frequency-dependent intensity data, a range of frequencies can be selected wherein fluctuations in intensity are characteristic of turbulence, even under difficult conditions where turbulence is cannot be naively detected. A detector is capable of relying on ambient light conditions to provide sufficient transmission and fluctuation to detect the characteristics of turbulence. Detection of turbulence aids in aircraft navigation and meteorology, analysis of industrial and commercial exhaust, and detection of unexpected fluid events such as containment leaks.