Well after seeing a plane spray here few years ago I did some research on it myself but its been a while. I can asure you what I saw had nothing to do with reduceing global warming since they probably werent 300 feet high when spraying. It would obviously not stay in the air long enoguh to do any good.
From the research I did then it seems the consistancy of these chemichal and metal sprays arent always the same their probalby experementing. However thier does seem to be one thing that is consistent in most tests, Barium as far as I know the only known use for it is to suppress the imune system. That may not be the only reason for the stuff but I'm sure its a big part of it.
This site claims that Barium in the atmosphre can cause it to heat up and suggests its used to cause the socalled greenhouse affect.
Some articles written here by ANONYMOUS claims its main purpose is mind control the disolving of the minds ability to discern between reality and imagination. Read all the links at the bottom by him. An interesting read.
Interestingly I live in the middle of nowhere nearest house is probably close to a mile away. They must realy be desperate to get everyone to spray out here. A friend said they were spraying again last week no wonder I have been sick again.