Clear air turbulence (CAT) is energy associated with gravity waves — phenomena in the atmosphere that look like ocean waves but which can occur in clear air. They can be created by air flow over mountains, frontal boundaries or other causes.
The type of gravity wave that John Knox, an assistant professor in the department of geography at the University of Georgia, and his colleagues identified as a possible source of airplane flight bumpiness comes from a different source; these waves are spontaneously generated and associated with jet streams at high altitudes, near cruising levels for airplanes.
Their new method outlined in the Journal of Atmospheric Sciences could help pilots chart new courses around these patches of rough but clear air that can turn an otherwise unremarkable flight into a nightmare.
