Jet Wash

• Backwash from jet engines can cause strong, but short-term, turbulence.jet engines and palms 2 image by Aaron Kohr from Fotolia.com
  
  A jet engine works by bringing air in one side and rapidly expelling it from the other side. This "jet backwash" is known as jet wash and can cause short-term turbulence.
  
  

Wingtip Vortices

• The shape of an aircraft's wing creates vortices at the wingtips.Airplane wing / clouds image by nwt from Fotolia.com
  
  When an airplane is in flight, lift is maintained because the shape of the wings causes air that passes over them to move more quickly than the air passing under them. This difference in air pressure creates a small vortex in the wake of each wing that lasts several minutes and can cause turbulence for other aircraft.
  
  

Wind Shear

• Cold air is more dense than warm air, so it drops toward the ground while warm air rises. If it strikes the ground with enough velocity, it can "splash" like a drop of water landing in a sink and create surface winds or wind shear that can interfere with an aircraft taking off or landing.
  
  

Jet Streams

• A jet stream is a river of quick-moving air that is created when a mass of low pressure air meets a mass of higher pressure air in the atmosphere. Wind in a jet stream is strong and often unpredictable and can cause high levels of turbulence.
  
  

Wave Turbulence

• Air passing over mountains can cause turbulence on the other side.copper mountain,colorado,rocky mountains,mountain, image by Earl Robbins from Fotolia.com
  
  When strong winds blow across a mountain range, they can create an effect similar to waves caused by ocean water flowing over a submerged reef. This can cause turbulence for aircraft flying over mountains.
  
  

Weather-Related Turbulence

• Strong currents are among the dangers in a thunderstorm.Lightning image by Mohamed Hayat from Fotolia.com
  
  Air in a thunderstorm often consists of various updrafts and downdrafts that can be a cause of severe turbulence, even causing an airplane to gain or lose thousands of feet of altitude. Because of this and other dangers present in storms flights are often delayed or rerouted.