Black Ops or Aerial Art 13/10/09 11.10am

I saw these this morning and thought it looked like the Battle of Britain up there! I just assumed they were vapour trails from planes. So is this a natural phenomenon anyone?

Happens all year doesn't it?! It is pretty cold up that high
I saw these trails in the sky too, along with two more being made by two planes flying vaguely in the same direction and actually crossing paths.

These are vapour trails, left by large jet engines. They happen at 30,000 feet or so.
Cirrus Clouds are above 23,000 and are natural - they are a layer of ice particles. Rarely they can drift/get blown into lines, but are quite distinctly different from vapour trails; if you plot the airlanes, you can discover the routes overhead. A number of them head for Paris, I know.

Whatever the lines are, they're making the earth lurch drastically!