turbulence

noun
tur*bu*lence \ ˈtər-byə-lən(t)s \
1595
  • the quality or state of being turbulent: such as
  • great commotion or agitation
  • irregular atmospheric motion especially when characterized by up-and-down currents

clear-air turbulence

noun
clear-air turbulence \ ˈklir-ˈer- \
1955
  • sudden severe turbulence occurring in cloudless regions that causes violent jarring or buffeting of aircraft
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