I used Photoshop to zoom in to the trails but have not altered the image in any way, shape or form other than that... I verify that I took these pictures with my iPhone in Mountain View CA. while driving on Shoreline Blvd. about 1/2 mile away from NASA Ames Research Center between 12:17-12:32pm on Tuesday September 23, 2013... The interesting thing about these pics, besides the unusual shape and size, is that they seemed to appear out of nowhere. No clouds in the sky, and no planes flying over to create these. Maybe someone has information about these, but I've never seen anything like this before.
Update: Check out this rotated and sheared photo from Andrew P. which indicates that the image was created by a skywriter.