We live under a relatively busy commercial air corridor. We see (and sometimes hear) jet liners and their vapor trails passing over in the sky above. In this case, they're coming from the north and flying south. Paris and Orly are to our north, so I suspect that many of these jets are coming from the Paris region. They might even be coming from places farther north like the UK and Scandinavia, others from North America even, all heading south toward the Mediterranean or Africa, and beyond! If the fates allow, I can sometimes identify a plane by using air traffic software. Very nerdy stuff, of course, but fun. This photo is not very good but, by zooming around, I can count at least six jets heading south.







