Lizbeth,
You just had to open this can of worms, didn't you?
OK. As I understand the chemtrail theories, either the government or the Illuminati are deliberately spraying chemicals into the atmosphere to make us unsuspecting fools more docile, reduce our mental capacities, or... a combination of other nasty dire consequences leaving us helpless compliant slaves to those who would control us. It's another conspiracy theory that conveniently dovetails into the over-arching "they're out to get us" grand theory.
FWIW, we do 'spray' chemicals into the atmosphere.

But it is unlikely that it is a directed sinister plot. Every airplane in the sky, from Cessna 180's to the biggest jumbo jets, use some form of hydrocarbon fuel that produces both observable particulates as well as 'invisible' gases. How these elements react with atmospheric moisture to form contrails, clouds, or just a general haziness can be explained, but only after-the-fact. We don't have the capacity to accurately track evaporation of sea water, or the specific measurements of the necessary particulates that allow molecules of moisture to coelesce into visible atmospheric conditions. So we can and do see visible reactions of human-made flitting about in the atmosphere. Any good meteorologist will readily concede that we can't predict EVERYTHING about atmospheric conditions because there simply aren't enough monitoring abilities available.
<edit> The comment that preceded my post confirms the impossibilty of any rational discussion, doesn't it?
BUT... The issue is making the jump from seeing the atmospheric conditions to assigning malovent intentions to unknown controllers. In this, you might as well talk to the wall. The people who are convinced that 'they're out to get us' cannot be swayed. They KNOW what we don't know, and build all the elaborate explanations necessary to support their theories - just like any other conspiracy theory, and any refutation is met with the usual put downs of being 'blind' to the evidence, not doing proper research that 'proves' their claims, etc. The chemtrail conspiracy people are pursuaded and nothing will change their minds.
Let this one go. It's curious, but no more curious than the dozens of other conspiracy theories.