WHAT IS TURBULENCE? Turbulence is what happens when the flow of air experiences a sudden disruption due to a change in wind speed or direction. It can occur in any fluid, from gases to liquids. We can see turbulent flow in rivers and streams, in steam rising from a boiling kettle, or even when we stir cream into our morning cup of coffee. And most of us have experienced mild turbulence while flying in an airplane; the plane is flying through a "sea" of air, and sometimes the "waves" are choppy. Many things can cause turbulence: rising warm air, thunderstorms, even strong winds blowing over the tops of mountains, buildings and other objects in its way. Extreme turbulence is caused by severe thunderstorms, tornadoes, or hurricanes; airplanes usually divert their courses to avoid such areas. Turbulence on flights can be annoying, but passengers are usually safe so long as they keep their seat belts fastened. The bumps and jolts don't generally affect the aircraft or its flight path. Severe turbulence can be avoided by flying around storm cells, or changing to a higher altitude.
GRAVITY WAVES: Atmospheric gravity waves are similar to waves on the surface of the ocean, but they are in the air instead of on water. The waves are set in motion by a disturbance in the atmosphere such as a change in the wind speed or direction, a sudden updraft from a thunderstorm, or a change in the jet stream high in the atmosphere. Atmospheric gravity waves act just like the ripples around a rock thrown into a pond. Gravity keeps the waves rolling.
The American Meteorological Society, the American Physical Society, the American Mathematical Society, the Mathematical Association of America, and the Institute for Operations Research and the Management Sciences contributed to the information contained in the TV portion of this report.