Jessica, it seems you’re talking about condensation trails. I never saw any alleged “chemtrail”, and if they were really existing, which is highly doubtful and implausible, why would they be visible ?
They would be visible because their purpose is to reflect the sunlight and therefore it's heat.
I also had a tough time with that Iquana because all aircraft that fly above the freezing level give off moisture which condenses into a fog which people call a condensation trail.
All cars/trucks and everything with an internal combustion engine give off vapour (which is visible when it condenses in below freezing weather) because hydrocarbons have water in them, from the process of distilling, etc.
http://www.casa.gov.au/scripts/nc.dll?WCMS:STANDARD::pc=PC_90762 The water is fairly close to the specific gravity of fuel, especially jet fuel, so it takes quite awhile to settle out and thus ends up going through the engine.
If observant, you will see someone, either maintenance or crew, draining some fuel from the bottom of the aircraft tanks, either daily or before flight, because the water eventually settles to the bottom of the tank. If the fuel is old or bad there may be a lot of water.
That is why in some areas of the world, you have to put gas line antifreeze (alcohol which is hygroscopic
http://medical-dictionary.thefreedictionary.com/hygroscopic ) in your car fuel so the lines do not freeze up in the winter.
Also aircraft that fly at high altitude, have to have fuel heaters in the fuel system to prevent the fuel congealing and the water from freezing, or you'd have regular engine flameouts.
Bottom line Jessica is that just because you see a contrail behind a jet doesn't mean it is spraying a chemical trail, any more than your car is doing it on a cool day.
For one thing putting chemicals in jet fuel has the unwanted side effect of coating the engine blades with the substance thus reducing it's available power. This is not a good thing. The aircraft I flew has a 150 hour limit between overhauls (typical overhaul is 3500 or more hours) of running gasoline through the engine because gasoline has lead added and the lead coats the blades. It is considered emergency only fuel.
Soooooo if this stuff is indeed being sprayed into the atmosphere it would have to be from aircraft with some sort of spraying systems that either inject it after the power section of the engine or it is sprayed from behind the wings like a normal crop spraying aircraft.
Since a politician here of repute (whether you like his politics or not) said it then...... ?
Iguana, After 9/11 there was no aircraft allowed to takeoff in North America. Within a short time everyone airborne was ordered to land. Even helicopters in northern Canada. During this period of time until permission to fly again was granted, the average temperatures in North America rose by a perceptible amount because the contrails from aircraft shade the earth (reflect sunlight back to space) particularly in high activity areas. If you find that hard to believe there is websites where you can observe all aircraft airborne in areas that the websites subscribe to the apropos ATC radar output.