How to find out if they are spraying above your head.
There are parameters for a contrail to form.
The temp must be colder than -38C.
The Humidity level must be above 55%
The warmer it is, the more humidity needed
to form a contrail.
I've made a chart using the Appleman Chart,
and the parameter set by NASA
I challenge anyone to find a sounding in the atmosphere,
between 8000-11,500 meters that fit the parameters to
for a contrail.
below 55%, contrails will not form, according to NASA.
above -38C, contrails will not form.