Darcy Corkal, age 11, of Dauphin, Aanitoba, Canada, for his question:
How is turbulence caused in the air?
Turbulence is a sort of temper tantrum that may disrupt the air, the ocean and even human affairs. Its baffling, unexpected changes seem to have no rhyme or reason but in all cases they must obey certain laws of cause and effect. We know what causes most ocean turbulence and aviation researchers have good reason to explore the causes of atmospheric turbulence. Let's hope that someday we learn what causes turbulent outbursts in human affairs.
The gaseous air is more restless than the watery ocean and both are more turbulent than the solid earth. This is because gases and watery liquids are fluids and easily moved. The filmy air is disrupted by heat and cold, by the earth's rotation, the seasons and by geography. All these factors set pockets of air in motion. When the airy disruption whirls in fast, unpredictable directions, it is called turbulence.
The laws of nature create enough atmospheric turbulence to keep the air in a state of upheaval though several miles above the ground. Nowadays, turbulence also is added by airplane traffic. A high flying jet creates sonic booms, plus a pair of turbulent wakes that follow its path somewhat like the watery furrow behind a ship. These pockets of wild activity are invisible in the clear air aloft. But the mighty waves of turbulence created by a large, supersonic plane could be fatal to a smaller plane following in its path.
Researchers study the causes and cures of this man made air turbulence. But the wildest turbulence is caused by nature and in this department, man made cures are out of the question at least until we know a very great deal more about modifying the weather. The turbulence in even a moderate thunderstorm may cripple a small plane and no plane can cope with the furious turbulence in a hurricane.
The major cause for all this gusty upheaval is in the nature of air. Its separate gaseous molecules use heat energy to speed up, spread apart and cause pockets of air to become lighter. Currents of light, rising air tend to form over warm patches of the earth, also when winds slide down a mountain slope and when opposite air masses collide to form cold fronts. The rotating earth spins the rising updrafts around and turbulent tantrums occur when currents of warm and cold air collide.
Every breeze creates a slight turbulence and a strong storm causes gusty turmoil far and wide. Special boundaries of turbulence form where a wind brushes alongside a wind blowing from another direction. These bouncy borders exist between the prevailing wind belts and also where the surface winds brush against opposite global winds aloft.
A plane needs cushions of air to lift it and hold it aloft. Its streamlined skin is designed to guide smooth, flowing air currents along its curves. Gusty winds with sudden changes in air pressure upset this delicate balance and the plane staggers and reels. A fraction of this hazardous turbulence is left in the wake of high flying jets.
Most of it is caused by the natural mixing and mingling of the global atmosphere.