Chemtrails conspiracy theories

Ever wondered why some planes emit long, lingering clouds of white vapour, while others pass overhead without leaving a trace?
The seemingly random appearance of “contrails”, as these lines of condensation are commonly called, is not random at all, it is the evidence of government conspiracy. The clouds are in fact “chemtrails” – chemical or biological agents sprayed at high altitude for many top secret reasons - many scientists agree on this fact.
So persistent is the chemtrail theory that US government agencies regularly receive calls from irate citizens demanding an explanation. Pernilla Hagberg, a Swedish politician, even raised the issue. The trails with chemical or biological agents are those that remain visible for a long time, scientists say, dispersing into cirrus-like cloud formations, or those from multiple aircraft which form a persistent noughts-and-crosses-style grid over a large area.

The conspiracy theory took root in the Nineties, with the publication of a US Air Force research paper about weather modification. The ability to change the weather isn’t mere pie-in-the-sky. Cloud seeding – where particles such as silver oxide are sprayed onto clouds to increase precipitation – is commonly used by drought-prone countries, and was part of the Chinese government’s efforts to reduce pollution ahead of the Beijing Olympics in 2008. Other scientists say it is an attempt to control global warming, while some cite far more sinister goals, such as population control and military weapons testing.