Causes of Turbulence
Wind flowing over obstacles such as mountains can cause turbulence. It is kind of like water flowing in a river with small eddies. A common winter time turbulence occurrence is called "mountain wave". This is produced downwind from a mountain range when the winter jet stream is at a lower altitude. The air mass in the mountain wave will flow up and down a little bit like sea swells (no, it doesn't make you "seasick"!). This can cause turbulence and is typical east of the Rocky Mountains. Weather forecasters are very good at predicting this type of turbulence because it is easy to track the location of the jet stream. Airliners may change the cruising altitude to minimize its annoying affects.
Turbulence can also be caused by shifting wind currents in the sky. When you transition from one wind current to another, such as crossing a warm or cold front, the air can get stirred up. Planes flying through these transition areas will normally experience some turbulence.
One of the more common types of turbulence is caused by "convective" heating. As the sun warms the ground, the hot air rises and makes the air have a "bumpy" feeling. You may see evidence of this by small puffy shaped clouds. This type of turbulence is normally limited to the lower altitudes.
You might feel "convective" turbulence for a short while after takeoff or before landing on hot sunny afternoons. It poses no danger and is rarely classified as anything but light or mild turbulence. Birds such as hawks and eagles use this rising energy of hot air to soar above fields. This way, they avoid having to flap their wings while searching for prey.
There are many sources of information about turbulence available to pilots. They get information from the National Weather Service, company Dispatchers, from ATC, other aircraft, and from their own observations of sky and cloud formations.
Car vs. Airplane Turbulence
Have you ever driven fast over a bump in the road which caused you to come up off of your seat an inch or two? It feels fairly violent and the jolt would certainly spill any drinks you were holding. How large of a bump does it take to do this? Maybe a one or two foot bumps in the road. But it feels pretty bad.
Airplane turbulence bad enough to spill drinks and cause you to come up off of your seat is very rare. But even if you do experience it, remember that the plane is not "falling" hundreds of feet. It just hit a bump a couple of feet high. The altimeters in the cockpit would barely register the bump. So try not to let your imagination get out of hand.
Next time you are driving on a bumpy road, imagine you were a passenger on a plane and how you would consider it to be "bad" turbulence. Now take a look at the road. How big are the bumps on the roadway to create the rough ride? The air is usually very smooth. But sometimes some small ripples can make it feel like "bad" turbulence!
So do like the pilots do - always keep your seat belt fastened while seated. Injuries can result from unexpected turbulence if you don't keep your seat belts fastened. Unfortunately, some flight attendants and passengers have been injured while standing during unexpected encounters with turbulence. It probably doesn't feel too good to have your head bang the ceiling of the airplane!
If you find yourself a little nervous about flying, there are many helpful resources available. Treatments methods available include virtual reality sessions, private therapy, classroom study, books, and tapes. There is also an online program created by an active airline pilot. If you have the jitters when planning your flights it might be worth a try to visit this free online course. It can answer your questions about weather, turbulence, flying over water, claustrophobia, losing control (panic attacks), terrorism, etc.
Turbulence may feel uncomfortable, but it is normal. People often misunderstand turbulence. When encountering turbulence, nervous passengers feel the plane is "falling" out of the sky. It is natural for them to only feel the "down" bumps. But for every "down" there is an "up" bump. The "downs" are just more easily noticed. Next time you are driving on a bumpy road, imagine you are a passenger on a plane and how you would consider it to be "bad" turbulence. Now take a look at the road. How big are the bumps on the roadway to create the rough ride? The air is usually very smooth. But sometimes some small ripples can make it feel like "bad" turbulence!
(Courtesy of the Fear of Flying Help Course - Fear of Flying Video: Prepare to Fly,
and Fear of Flying Book: Wings of DIscovery)