This is a featured picture among the finest imagery on the English Wikipedia Web site. It shows the turbulent air flow from the wing of an agricultural plane. The red smoke traces the wake vortex "which exerts a powerful influence on the flow field behind the plane." For this reason, the FAA requires that planes keep a safe distance behind each other when they land.
But turbulence in the sky is having detrimental effects to passengers and cabin crew members. A recent news report by the Civil Aviation Safety Authority (CASA) says "there are nearly a dozen serious incidents every year." The problem, according to the CASA report, is pilots, crew members and passengers all need more effective means for communicating in turbulent skies. Whether or not passengers will listen to crew members is another story.