Notice the dissipation of the trail within approximately a 30 second interval. The camera was held stationary on the contrail after the plane passed. Notice that none of the trails are coming directly from the tail of the airplane.
Another set of contrail pictures is presented that can be used as a control group when making comparisons to other types of aerosol sprays.
Various pictures of normal contrails are presented and discussed in the paper. Notes are presented outlining how to tell a normal contrail from other aerosol spray lines.