Abstract:
An improved clear air turbulence (CAT) detector (100) sensing infrared radiation in the 27-33 micrometer range of the water vapor rotational wavelength band. The improved clear air turbulence detector (100) for use on an aircraft includes a forward looking and upwardly oriented between 8 to 12 optical assembly (300) having a thallium bromoiodide infrared lens (410), a 27-33 micrometer wavelength interference filter (420) and an infrared detector (430); a radiometer amplifier (320) for amplifying the output of the optical assembly (300) and for generating an analog voltage signal (330) related to the received infrared intensity, a processing unit (340) for analyzing the analog signal, and a display unit (360) for generating a first signal (370) when no clear air turbulence is detected, a second signal (380) when a moderate turbulence is detected, and a third signal (390) when extreme turbulence is detected. A method for determining the advance time for entering the clear air turbulence after detection is based upon the altitude of the aircraft.