The trail of clouds left by a plane crossing the sky can be fascinating to children and adults alike. Air traffic has become so common that it is not uncommon to see persistent streaks in contrast to the blue of the sky or blurring in the clouds.
Although many consider them an interesting but very common phenomenon, there are those who are alarmed by them. Concerns range from the idea that these trails could exacerbate global warming to more elaborate theories, which hold that some governments (or who knows who) have been dumping harmful substances onto the earth in secret.
The scientific explanation
Jet engines blow very hot air, and since water vapor is one of the by-products of exhaust gases, that air is also very humid. However, in the upper atmosphere where these aircraft fly, the air is usually very cold, often with temperatures below 0 ° C. When a jet engine is spitting hot, humid air into an environment that is cold and has low pressure, the result is condensation. The water vapor that comes out of the engine quickly condenses into drops of water and then crystallizes into ice. Ice crystals are the clouds that form behind the engine.
This is why the streaks are called stelae, short for "contrails." To help explain it, scientists invite us to compare it to our own breathing on colder days. If the environment is humid the steam condenses, however the puffs of breath dissipate quickly on the driest days. The same can be said of contrails: when the environment is more humid, the contrails remain, but when the environment is dry, the contrails disappear more quickly.
This explanation makes sense. But the contrails consist not only of ice crystals and water vapor, but also other by-products of engine exhaust. These include carbon dioxide, nitrogen oxides, sulfate particles, and soot. For this reason, many voices point out that these elements can have negative environmental effects.
The theories of Chemtrails
A fact sheet from the United States Environmental Protection Agency explains that the trails, even long-lasting, are simply traces of condensation and are not harmful at all, even though they do not deny their content in harmful elements.
However, there are those who think that it is at least a "suspicious" fact that the contrails ejected by airplanes today are thicker, dense and remain suspended for longer than they did in the past.
Another fact that draws attention is that sometimes the tracks are not horizontal as one might expect the contrails of an airplane to be, but they have capricious shapes: circles, spirals and crisscrossings.
These "oddities" have led many people to suspect that "someone" has placed other substances in them, transforming them from harmless trails into Chemtrails (chemtrails). Those who believe that there is something abnormal about the new stelae have proposed various theories to explain what the authorities could be covering up.
The most extreme see in these Chemtrails an evidence that connects the epidemics of certain diseases like the flu, to the cases of the stelae. There is also talk that the land is being sprayed with products such as barium salt in order to aid in radar mapping for defensive purposes.
However others propose that it could be experimenting with the manipulation of the climate. Actually, this is not as fanciful as it may seem. As early as the 1950s, the British were able to successfully "seed" the clouds with salt, dry ice and silver iodide, in order to bring about rain.
Another popular theory is that Chemtrails are well-intentioned attempts to combat global warming or the destruction of the ozone layer, by spraying particles that would reflect the sun's radiation.
The truth is that anyone who takes the trouble will be able to find a good number of “home” videos and photos on the Internet, showing long trails in the skies across the country left by airplanes and about which the authorities have not given any explanation. "Convincing", although many climate scientists argue that they are simply jets of condensed water vapor.
In summary, making use of a healthy skepticism, forgetting paranoia and conspiracy theories and simply sticking to reality, it would be very positive to know (with serious studies and based on reliable and scientifically proven evidence) if these trails are ultimately a cause for concern.