Contrails can be, and most often are, caused by water vapour condensing out the back of the gas turbines that power aircraft. These engines are basically giant air compressors, and the gas that leaves them isn't necessarily the same pressure that it entered as. Plus it can be seeded by particulates from normal engine running.

You're looking at a cloud bro, try not to huff the paint cans before writing next time. 

 Thanks for the patronising answer and no that wasn’t what I’m talking about 

 You asked what they were spraying. They aren't spraying anything, it's normal for these to appear