# Panic at 35000 Feet : Turbulence

Updated on June 27, 2019

You're flying at 35000 feet, trying to have a refreshing nap before you land at your destination and suddenly the aircraft starts rattling. As the upheaval continues, the pilot turns on the seat-belt sign, and for the next few minutes, especially if you're an irregular flyer, your anxiety soars. However, it all ends well, and you thank the lord for not bringing those disturbing thoughts in your mind to reality.

Turbulence occurs quite frequently, and most flyers at some point are likely to encounter the wreck. So, what are its repercussions, and if you experience one, is there a chance of a flight accident? To answer the queries, let's first understand what turbulence is, and what might cause it.

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## What is turbulence?

Turbulence, in simple words, is the violent or unsteady movement of a fluid. Any fluid has two types of flow: laminar and turbulent. While many may not be aware of the technicalities of these flows, everyone has observed them. Haven't you noticed how the appearance of water changes from transparent to cloudy as you slowly open up a tap? As the colour changes, the flow also shits from laminar to turbulent. Similarly, smoke emerging from a candle is initially resolute (laminar) but muddles as it rises (turbulent).

Imagine water or any other fluid to be composed of multiple thin layers. In a laminar or streamlined flow, there is no disarray between these layers, and the particles in every layer follow a smooth, non-interfering path devoid of any perpendicular swirls. Turbulent flow, on the other hand, is chaotic. Due to pressure imbalances, velocity or other factors, the layers disrupt, resulting in a disordered flow.

Osborne Reynolds, in 1883, gave a formula determine the nature of the fluid flow mathematically. Any fluid has mainly two types of forces, inertial forces which, as the name suggests, combat disturbances in the fluid's movement and viscous forces which offer resistance. The ratio of these forces (inertial to vicious), called Reynold's number, is used to determine the nature of the flow. If the number is more than a critical value, around 4000 in most cases, fluid flow is deemed turbulent.

## What causes turbulence?

According to various sources on the net(National Geographic, Popular Mechanics), the most common causes of turbulence are landscape or mountains, storms, and clear-air turbulence.

MOUNTAINS

Like ocean waves crashing tumultuously against rocks on beaches, air flowing on top of a mountain also causes turbulence in the form of waves as it reaches the other side. As this is a recurrent phenomenon in mountainous regions, pilots are generally ready to tackle it.

STORMS

Turbulence due to thunderstorms or bad weather is fairly intuitive. As the storm clouds expand, they push air away, generating waves that break into turbulence. Again, with the help of weather forecasts and radar systems, pilots can generally avoid excessive disturbances.

CLEAR-AIR

Clear-air turbulence cannot be perceived in advance, making them the most treacherous kind of turbulence. Mainly caused by the shift of the boundary between jet-stream and the slower-moving air adjacent to it, it can be a havoc for flight attendants and passengers too at times.

## Will your plane fail due to turbulence?

As frightening as it might seem, turbulence is not very dangerous. Sure, it is uncomfortable, can splash out your drinks, cause injuries if you're caught standing during one, but it isn't going to bring the plane down. Hardly few crashes in history, for instance, the 1966 British Airways crash near Mt. Fuji, have been caused due to turbulence and none in the last forty years. Modern airplanes are designed to confront much more hazardous conditions.

Furthermore, most turbulence, apart from those caused by the jet streams(as we have previously learnt), can be predicted, and pilots can reroute if necessary. Buckling the seat belt for the entire flight and avoiding seats at the backside in a plane, are some precautions passengers can take to ease the inconvenience.

While it's relieving to know that turbulence is not life-threatening, one must be ready to encounter them more frequently in the coming years. Due to climate-change induced by the chaos that humans have created in nature, weather patterns have suffered, which has resulted in the rise of turbulence. They have increased by 40-90% over Europe and North America since 1958 and are expected to get worse (source-business insider).

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