Observed unusual contrail very high above the Mall between the Museums. It ran North/South,was white in color against the blue sky and had what appeared to be circles or lines across it running East/West at equal intervals across the entire visable length. It was not other contrails cutting across it. They were short lines. I have never seen a contrail anything like this ever and have no idea what produced it and there has to be lots and lots of other observers. I dont know if an aircraft or type of UFO produced this,but if airplane,its not anything I have ever seen before. NOTE: I come from an aviation family,have been flying,and flying in planes my entire life and for me to make note of a contrail after seeing countless thousands,(some up close),then it has to be something that is significant and very very strange.