Chemtrails aren't anything more than a daft made up conspiracy theory, largely coming from those that must have failed school science. The chemtrail conspiracy theory says that the typical longer lasting condensation trails (contrails) from aircraft are “chemtrails” that comprise of chemical or biological materials left in the sky and are sprayed for sinister reasons. Those that believe in this concept (chemtards) declare that whilst normal contrails dissolve somewhat quickly, contrails that linger will need to include additional substances to make them keep going longer. They hypothesize that the reason for the chemical discharge is likely to be for many sinister and not so threatening motives for instance management of solar radiation, climatic conditions manipulation, psychological manipulation, control of the human population, biological or chemical rivalry. Additionally they are convinced that the chemtrails are causing respiratory: conditions and other health issues in the human population.
All of the assertions produced can be easily ignored and the scientific community have discussed contrails and replied to the fringe movement. There is certainly simply no proof which the supposed chemtrails differ from standard water dependent contrails which are normally left by high-flying aeroplanes under certain environmental conditions. The conspiracy theory is still there in spite of scientists and government departments around the world having regularly explained how the supposed chemtrails are only in fact usual contrails. This does not seem to have made any impact on those that rely on the conspiracy theory.
Another way of thinking about it, is that if it turned out legitimate, then this would need to happen to be agreed to by every country on the planet. Each and every main airline in the world would need to say yes to spray chemtrails. This can require large numbers of pilots in addition to airport employees, climate forecasters and experts, every University which has a meteorology or atmospheric science department and every business that monitors quality of air. They will all have to agree to stay silent. This may be an unparalleled worldwide task and co-operation that anyone who is driving it, if it was true is worthy of a Nobel prize. Nobody who is convinced in the fringe movement of chemtrails (ie the actual chemtards) has been willing to explain how this exceptional co-operation is actually working with not one person spilling the beans about it.
Another means of looking at it can be simply the facilities of supplying the chemtrails if it was true. It has been estimated what would be needed to only spray the USA with the presumed chemical compounds which are believed by the chemtards as being used. It had been calculated that the government would have to arrange four million 747 flights to disperse their chemical compounds each week for this to be effective. That's 18 times more flights daily than in the entire US. In addition their will have to be the facilities and staff to support this type of considerable venture (that is going to also have to keep quiet about what they actually do). Also, this will only be for the USA and a similar infrastructure will be necessary for every country on the planet. Probably none of these believers in chemtrails has been capable of explain this.