About 4 or 5 years ago, I took the dogs out just as the sun was setting, and stood on the deck around the above ground pool, and heard a plane that sounded like it was in distress; there was a small airport nearby so I expected to see one of the prop planes that flew out of it. Surprised to see a old military jet flying low and slow one mile south of me, not far above the treetops; when it was parallel to my position I could see that it had no markings whatever, and appeared to be painted white. The 'distress' noise- kind of a concussive popcorn sound, was something being sprayed that exploded in the hot exhaust and formed a cylindrical cloud about 10-15 ft across, that expanded very slowly over time. In an hour it was probably 50 ft across; it was an unusually still night and it did not disperse. I got in the car and drove for at least 5 miles east, and the cloud still disappeared in the distance- and it followed the road. I drove back home, and I watched it until it was fully dark (no moon) and I couldn't see it any longer. That night I dreamed it was a cloud of poison that settled on the ground.