I did. They are common comercial airlines.
Another observation was that when it happen, it is comming from all of the airplanes in the sky at that moment.
Discussion
This alone would suggest that it is due to the atmospheric condition. Perhaps they are just con trails. But it is weird how large they are. I have seen several times how they descend from that high altitude and become progressively larger. After a few hours of planes flying above they cover the entire sky.
btw I hate the term chemtrails, as it presuposes the conclusion of what we are trying to find out. Whoever say it sounds like a retard.