Clear Air Turbulence - Detection

Detection

Clear-air turbulence is usually impossible to detect with the naked eye and very difficult to detect with conventional radar, with the result that it is difficult for aircraft pilots to detect and avoid it. However, it can be remotely detected with instruments that can measure turbulence with optical techniques, such as scintillometers or Doppler LIDARs.

Although the altitudes near the tropopause are usually cloudless, thin cirrus cloud can form where there are abrupt changes of air velocity, for example associated with jet streams. Lines of cirrus perpendicular to the jet stream indicate possible CAT, especially if the ends of the cirrus are dispersed in which case the direction of dispersal can indicate if the CAT is stronger at the left or at the right of the jet stream.