Weird "Clouds"

While visiting relatives in Severna Park, Maryland, I bought repair hardware the Home Depot on Mountain Road, north of the Md2 / Md100 interchange.

Leaving the store, I noticed a row of strange "clouds" in the WNW sky, about 14 long narrow clouds, parallel and evenly spaced. I presumed these were a strange natural phenomena, and took a picture with my wife's screen phone.

I returned to Oregon a week later, and resumed reading a library copy of "Escaping the Rabbit Hole", 2023 by Mick West. I started reading chapter 7 "Chemtrails", and realized that the aircraft contrails described in the text and illustrated on the first page of the chapter strongly resembled the dozen-plus "skinny clouds" that I saw. BWI airport was to the west, which is a major hub for Southwest Airlines, with its vast fleet of nearly identical 737-800 aircraft, each seating 100 passengers and usually full.

I presumed the Southwest aircraft fleet is automated enough that they can bring in a long line of aircraft for landing, accurately spaced 3 minutes apart. That day, each successive aircraft landed northbound through a wide river of air (I assume) moving east (towards me), with a central stream of cold air fostering contrail formation. When the next aircraft landed, the cold air had moved east just enough to create the spacing I later saw in the sky, successive aircraft after aircraft for perhaps forty minutes.