Trails in the Sky: Secrets of Airplane Contrails

Discover the secrets behind airplane contrails in “Trails in the Sky.” Learn what contrails are, how they form, and the factors affecting their duration. Explore the role of kerosene and additives like aluminum in creating these sky phenomena. Uncover the science of water vapor crystallization and its impact on our atmosphere. Read the following EasyDaily Text.

What are contrails?

The trails you see in the sky are mostly water vapor that crystallizes at temperatures between -50 to -60 °C.

How long do contrails last?

The duration of these trails depends on:

– Flight altitude: the height at which the airplane is flying (or the temperature at that altitude)
– Weather conditions: the weather conditions at that altitude (whether there is wind and its strength)
– Type of kerosene: which varies depending on the standards of the producing country.

How are contrails formed?

Isn’t kerosene always the same everywhere?

Did you know that you fill your car with different fuel, not just every time but also depending on the season?

Although there are standards, variations in oil fractions lead to tolerances during the production of petroleum derivatives. There is winter and summer fuel that contains different additives tailored to weather conditions. These additives help prevent the fuel from freezing in winter or evaporating in summer, and they also affect engine performance and exhaust emissions.

Why are additives used?

Once, lead was present in gasoline as an additive (tetraethyl lead), while today, unleaded gasoline with an octane rating of 95 or 100 is used. Additives are added not only for freeze and evaporation resistance but also to prevent uncontrolled combustion before the necessary moment when the spark plug ignites in gasoline engines, or when the pressure for self-ignition is reached in diesel engines.

Where does the water in kerosene come from?

The chemical formula of kerosene is mainly C12H26−C15H32, but it can vary and be C9H20−C14H30. This affects the results of chemical reactions and the amount of water vapor in the exhaust gases.
During the combustion process, the following reaction occurs:
½ C12H26−C15H32 + 29O2 → 27CO2 + 58H2O
Water crystallizes instantly at temperatures between -50 to -60 °C, creating a white trail.

The magic of white powder in the sky

Finally, what you might be most interested in is the addition of aluminum as an additive. It is used for releasing a larger amount of heat during combustion and reducing fuel consumption. Aluminum is added in the form of Al2O3, which reacts with H2O during combustion, creating aluminum oxides and hydroxides, the most common being aluminum hydroxide (AL(OH)3) in the form of a white powder that is dispersed with the exhaust gases.

Al2O3 + 3H20 → 2Al(OH)3