They're chemtrails. They spray them over population centers every single night and sometimes during the day. The government and multiple universities have admitted to using commercial airliners to spray the sky with chemical concoctions under the guise of stopping global warming. But they could be spraying anything up there like lithium respiratory irritants. They could kill off entire cities over night if they really want to.

At least you noticed the lines in the sky above your head though. Most people do not.