Clear Air Turbulence (CAT) 2 : Turbulence that occurs in clear air and not associated with cloud formation, such as that associated with winds at low altitudes and with the jet stream at high altitudes
Ilan Kelman (ed.), Vulnerability and Resilience Definitions and References, Version 2, 2007. http://www.islandvulnerability.org/docs/vulnres.pd f, (Vulnr and Resilience - Brit) {524}