Contrails can last all day. There is continuous cloud cover from them over many countries because of the magnitude of planes flying the same routes.
I had not before witnessed such a dramatic change from clear blue skies to overcast weather before, all due to airplanes. It wasn't a particularly humid day, and I haven't seen anything like it since.
Right now I can see short, temporary contrails from high altitude jets overhead. If the weather was different (at 40,000 feet) there would be lingering contrails. I live in a high traffic area, both military and civilian jets. They are always flying. On days with no contrails you can't even see them. On days with the right weather conditions, they form an overcast.
If this is true, that overcast weather is an incidental consequence of condensation trails in high air-traffic zones, then what does this say about the feasibility of weather control?
After 911 when the skies were clear, measurements found weather changes are directly attributable to contrails, visible or not. That much cloud cover changes both the heating during the day, and the cooling at night. During WWII contrails were considered as a weapon, to block sunlight over Germany, to destroy crop production.
That's interesting. Do you have a source relating how the weather changed after air traffic was grounded post 9/11?
On a bad day commercial flights create an overcast over large areas of the US and Europe. It isn't on purpose, but it sure as hell effects those below.
Well, I have to accept the possibility that what I saw was harmless condensation. On the other hand, I'm not completely convinced.