See comment further above. Persistent contrails have been around since the 50s. It is all a matter of being formed at high-er altitudes, where the air is more saturated and it is difficult for a cloud to dissipate. Just a fact of airplanes being able to fly at higher altitudes due to better engines.
See comment further above. Persistent contrails have been around since the 50s. It is all a matter of being formed at high-er altitudes, where the air is more saturated and it is difficult for a cloud to dissipate. Just a fact of airplanes being able to fly at higher altitudes due to better engines.