Contrails are real, chemtrails are not
Contrails are produced from the exhaust emissions of aircraft. They have been recorded from the early days of aviation when the first aircraft reached significant altitudes. They can be formed from piston engines as well and modern jet engines. In fact, modern high bypass jet engines are much more likely to produce contrails than the older engines common two to three decades ago.
Some contrails dissipate fairly quickly while others persist for hours. Why?
Current research indicates that persistent contrails form in regions of the upper troposphere known as “Ice super saturated regions.” (ISSR).
Ice super saturation means that the relative humidity with respect to ice is greater than 100%.
The passage of an aircraft through one of these regions does several things. The engine exhaust injects warm water vapor, and aerosol particles from the fuel combustion into the air. The wake turbulence produced by the aircraft’s passage serves to mix, turn and disturb the air mass. These factors combined with the extreme cold (generally below -40 degrees) of these areas combine to produce the classic ice clouds of contrails.
Chemtrails on the other hand are an urban myth, born out if ignorance and fed a diet of pseudo science with a huge helping of “conspiracy theory insecurity syndrome.”
There is little or no logic to chemtrail theories and there is certainly no science behind them.
In fact, the whole “chemtrails” phenomena as a conspiracy theory jumped the shark about 7 years ago. No one seriously gives it much thought these days other than to point out the inconsistencies and cognitive dissonance employed by the true believers to maintain their faith.