The white streaks left behind by airplanes in the sky, known as contrails or defractory trails, are a result of a complex mathematical equation. To understand the formation of these grooves, we need to consider two key factors: clouds and engines.
Clouds form when air condenses, which occurs when its humidity reaches 100%, and this can only happen at extremely low temperatures. Commercial airplanes fly at an altitude of around -56°C, where the temperature is just low enough for condensation to occur. As the airplane moves through the sky, its engines generate a thrust force by burning fuel and oxygen, producing combustion gases and water vapor. The hot water vapor then condenses and freezes onto tiny particles in the air, creating a snowy trail that follows behind the plane.
The last component of this equation is the expansion of gas as it leaves the plane’s engine. Inside the engine, the molecules are highly compressed, but when they exit into the open air, they expand rapidly, causing a shock wave that can create visible contrails.
Contrails are often referred to as “Anglo-Saxon” because of their use in weather prediction. By studying their nature and persistence, scientists can predict changes in atmospheric pressure and temperature that could lead to storms or other weather phenomena.
Not all planes leave contrails behind them – it depends on their efficiency. A turbojet’s efficiency is measured by how much work it produces relative to how much chemical energy it uses up in doing so. This efficiency is closely related to contrail formation – if a plane’s engine is not working efficiently enough to produce enough thrust force for flight, it may not be able to generate enough combustion gases or water vapor to create visible contrails.
During air shows or other public displays of aircraft technology, pilots may intentionally leave colorful contrails behind them by mixing dyes with exhaust gases and releasing them at just the right moment. These “polychrome grooves” are not true condensation trails but rather artistic creations created through clever engineering techniques.
Finally, there is an exciting type of contrail left behind by supersonic planes traveling faster than sound: Prandtl-Glauert condensation clouds formed as a result of sudden drops in air pressure caused by high speeds exceeding Mach number 2 (the speed of sound). These clouds take on unique shapes like disks or cones and offer fascinating insights into how aircraft technology continues to push boundaries in our atmosphere.