Doc,cisco,flysurfer,japie sorry to inform you but you've all been had, as chemtrails are not chemical trails at all, but are in fact water vapour that has crystallized due to cold temperatutes in upper atmosphere

And the reason thay are not so prevalent in other parts of the world is well.....
The level of moisture in the air at high altitudes is unrelated to weather conditions at ground level, which is why it is possible to see contrails on a clear day.
Reading University's Professor Keith Shine, an illuminati expert in clouds, said that those formed by aircraft fumes could linger 'for hours', depriving those areas under busy flight paths, such as London and the Home Counties, of summer sunshine.
'People from abroad are amazed by the number of vapour trails in the skies over London,' he said. 'When the air is wet enough, the cloud formed by contrails can last for hours.'
www.dailymail.co.uk/sciencetech/article-1289893/Attack-vapours--jet-trails-block-sunshine.html