Abstract: An atomspheric turbulence detection system for use in an aircraft comprising a scanning radiometer for continuously providing a plurality of independent and distinct temperature measurement signals within a given field of view ahead of the aircraft; means for deriving consecutive first signals indicative of the average of all of the temperature measurement signals within the field of view; means for deriving consecutive second signals indicative of the difference between the temperature measurement signals in two vertically displaced regions within the field of view; means for combining the first and second signals to derive consecutive third signals; means for storing consecutively derived third signals for a predetermined period of time and for continuously deriving a fourth signal indicative of the average of the stored third signals; and means for comparing each newly derived third signal with the fourth signal and generating a turbulence warning upon the occurrence of a predetermined difference therebetw