Turbulence is caused by the convergence of two or more wind currents in one area where the plane happens to be flying through.  It can happen at any altitude, and it is mainly the weather and quick temperature changes that causes air turbulence, which in turn causes airplanes to act like bucking broncos, dropping a few hundred feet or more within the span of a few seconds.  Turbulence can be a few minor bumps, making it seem like the plane is driving over speed bumps in the heavens, and turbulence can also be a major drop in elevation in a second or two, caused by crossing from one air stream into another, with the air streams coming from different directions.

A perfect example of turbulence is when an airplane flies over the Rocky Mountains, and is buffeted by air currents of different strengths from every conceivable direction, especially from the Pacific Ocean.  Air currents that go up, down and sideways can rock a plane silly, and flight paths are changed to avoid problem areas.

When stating that weather is responsible for turbulence in aircraft flights, we must remember that air currents are considered a part of the weather system.  The most dangerous types of turbulence are major storm systems, with huge black (over-saturated) clouds, especially when they are electrical in nature, or cyclical, as in tornadoes and hurricanes.  When a plane enters an electrical rain storm, it exposes its frame to extreme conditions, which could easily tear the plane apart.

Turbulence from major storm systems is why, when severe weather systems are in the way of an airplane’s regular route, they tend to fly around the storm, in the shortest and safest route possible.  This is usually preceded by an unpopular announcement from the pilot that the flight time has been increased by an hour or three.

Turbulence can also be caused by passing between two or more air currents that are either at different speeds or different directions to each other.  This can be very dangerous, and was suspected to be the reason for the aircraft that lost the upper portion of the cabin, right by the front emergency door, and sucked out a stewardess into the sky, along with some seats and other loose articles.

Another form of turbulence is caused by passing through the wake of another aircraft, especially the higher-powered super jumbo jets, like the 777 Dreamliner, or the newer Airbus A380 design, which carries 873 people in the family configuration.  When a smaller plane, like a Cessna, passes through the turbulent wake that a more powerful jet leaves behind it, the craft can lose all control and plummet to the ground, or be torn apart in the sky.  This is one of the major reasons that smaller aircraft fly at much different altitudes than jumbo jets.  This type of turbulence usually causes the plane to rock side to side, as opposed to up and down, down, down.

Aside from storm cells, mountain ranges and the wakes of other planes, turbulence can also be caused by hot air rising from the ground, getting colder as it rises and mixing with the air that is at a higher elevation.  Another hot-spot for turbulence is above airports, where planes are forced to fly in waiting patterns for the planes that arrived ahead of them to land.  The only way a plane is going to jump the queue is to declare an emergency.  Waiting in a circular holding pattern with a lot of other large planes can cause a wind swirl, but nothing bad enough to declare emergencies, as long as the pilots are certified.

However, other than the not so common freak accidents, turbulence should cause no major problems to the aircraft, as would a flock of Canadian Geese.  The passengers, on the other hand, can experience many different maladies, from air sickness to vertigo, from passing out to a major ear problem (either clogged or popping).  There is medicine for air sickness, ask the flight attendants if you do not have your own.  And, if you do get sick due to turbulence, try to be brave.  Crying, moaning and groaning will only make the other passengers feel worse than they already do, and bemoan you for it.

Fly informed.  Fly safe!