Every passenger on a commercial airline will sooner or later have the experience of seeing the "Fasten your seat belt" light sign suddenly turn on (the well-known "fasten seatbelt sign"), while the captain announces in a calm voice the imminence of rough areas. For the majority of serial travelers and commuters, this just means attaching a boring buckle. But for those struggling with previous anxiety and fears, it seems like the beginning of an irreversible catastrophe. Let's immediately remove the veil of misunderstanding and try to discover scientifically: What exactly is the atmospheric turbulence that causes thousands of tons to bounce around?
Why Does the Plane Shake in the Clouds?
You tend to imagine a plane as a sort of rocket or spaceship traveling motionless and muffled in deep space or an astronomical "vacuum". There is nothing more wrong for understanding meteorology: a Boeing or an Airbus look strikingly similar to a gigantic boat, or a submarine, cutting through the middle layers of an immense ocean. Air is, by scientific definition, a gaseous fluid.
Invisible Waves in the Atmosphere
Like any fluid existing in nature, air presents a continuous state of movement and transit dominated by thermo-dynamic exchange. Now imagine the bed of a stream: when the peacefully flowing water encounters sharp rocks, inlets, differences in height and submerged boulders along its path, it will create vigorous whirlpools and waterfalls of very white water. The same precise and identical physical laws apply to cruise altitudes in the stratosphere and troposphere. An airplane traveling at 800 kilometers per hour "bounces" and surfs on these air waves generated by wind variables exactly as a large yacht or patrol boat bounces without any damage when crossing the choppy wake of a colossal ocean liner offshore.
Classifications, Causes and Origins of Turbulence
The World Civil Aviation (ICAO) classifies three different macro categories, each generated by distinct atmospheric peculiarities (and largely predictable from the accurate use of radar):
- Thermal or Convective Turbulence: It is the typical progenitor of the purely summer period of hot afternoons. Under the direct blows of the sun, the desert, the asphalt of metropolises, and above all the arid lands heat up, forcefully raising the torrid and light air (fiery upward currents). At higher altitudes the returning cold air impacts the hot towering spray at great speed, forming large cumulus clouds.
- Integral Orographic Turbulence: It collects disturbances resulting from intense winds pushed "downwind" towards rugged topographic extensions. Colliding with the tops of Andean mountain ranges or Himalayan and Swiss peaks, the surging air bounces several kilometers higher, breaking vertically into waves known as the Orographic Standing Wave Effect.
- Turbulence in "Clear Air" (CAT - Clear Air Turbulence): This in itself is the "most feared" turbulence of a technical nature since, not being able to have cloud trails from watery condensations or thick hailstorms, the on-board radar crosses it in the total blue sky and for the human eye of the pilot it does not appear transparently visible on the horizon. It acts on the cross-border bands of the great Atlantic routes caused mainly by the monstrous gap between the powerful Jet Streams. Today, various simulators and AI algorithms support predictions with astonishing accuracy, providing preventive information nautical miles in advance.
Engineering vs. Fear: Airplanes Are Invincible In The Air
Having made these clarifications of a climatic nature, let's move on to the decisive topic of safety and general phobia of panicked passengers: less than the minuscule 4% of injuries declared in the aeronautical hospital phase have historically resulted from violence and jolts attributable to the sudden turbulent jolt. There is more to say: among the wounded practically the absolute totality was out of place at the wrong time and with the retention belt strictly dangling without a re-fastening.
Wings That Never Break
No certified commercial class aircraft has ever suffered wing shearing in the sky, nor slight melt collapses, nor vertical failures in the entire last thirty years attributable to pure and intact atmospheric turbulence or disturbances. The incredible elasticity of titanium combined with structural carbon fiber, aluminum and composite alloys form the heart of today's Boeing or Airbus jewels of the air. The videos present in public form from the secret laboratories confirm that the hydraulic balancers tend and arch the wing of a civil tri-jet well beyond and beyond 90° of elevation, simulating resistance up to the formidable winds twice as high as the worst cyclones and hurricanes, all before reporting a partial crack of engineering construction micro-lesion. As abrupt as the changes may seem to your scared, seat-locked muscles, the plane sails at your convenience G forces irrelevant for the structural steel of the internal skeleton.