Tomas Daniska recently sent in this photo, snapped on his phone after landing at Trencin Airport (LZTN) in Slovakia.
“It shows an interesting phenomenon,” he explains.
“There are two contrails from two airliners. One is straight as usual and the other, being previously straight as well, has hit a boundary of two air masses and became pretty sinusoidal, visualising the air ‘waves’ up there. Though they seem horizontal from the ground, the waves are probably vertical and the two jets have flown different altitudes, hence different outcomes. It took me a while to realize it’s pictureworthy so the wavy contrail is a bit dissolved, but still pretty much visible.”