The contrails, or white grooves left by airplanes in the sky, are a result of a complex polynomial involving various factors. Firstly, clouds form when air condenses, which occurs when its humidity reaches 100% and the temperature is extremely low. Commercial airplanes fly in the highest layer of the troposphere, where temperatures can drop to around -56°C.
Secondly, the engines play a crucial role in the formation of contrails. Airplanes use their engines to generate thrust force and burn fuel and oxygen to do so. The hot water vapor produced during combustion condenses and creates the snowy trail that we see behind planes. Additionally, as gases expand when leaving the plane, this also contributes to the formation of contrails.
Contrails are called “contrail” because they are a contraction of “condensation” and “trail.” The next question raised by this physical phenomenon is why not all airplanes leave a wake. The efficiency of an airplane’s engine is measured by its coefficient between work done and chemical energy produced. An interesting aspect about contrails is that their nature and persistence can be used to predict weather conditions.
Sometimes during air shows, we see colored contrails called polychrome grooves, which are achieved by mixing dyes and releasing them at just the right moment. These are not true condensation trails however. Finally, there is a very striking type of contrail: those left by planes traveling faster than the speed of sound, forming cloud-like shapes that take on disk or cone forms. These clouds are called Prandtl-Glauert condensation clouds and are formed as a result of sudden drops in air pressure.
In summary, contrails are formed through a combination of factors such as humidity levels, temperature drops in high altitude layers of the atmosphere where commercial planes operate; engine combustion processes which release hot water vapor that condenses; expansion of gases as they leave aircraft; colorful polychrome grooves created by mixing dyes at specific times during flights; and unique cloud formations due to sudden drops in pressure while flying faster than sound which lead to Prandtl-Glauert condensation clouds.