The picture to the left was found when I did an image search on google for the term Contrail.  A Contrail is a Condensation Trail that is left by a jet engine.  You’ve probably seen them if you’ve looked up into the sky.  Some contrails last for a matter of seconds and some seem to persist and spread to form a cloud layer.  There have been some scientific investigation with regards to the weather and climate modification affect of these persistent contrails.  Below are some links to articles regarding this :

There hasn’t been a great deal of scientific exploration with regards to how contrails (especially persistent ones) might cause changes in weather systems, one thing that is clear is that these persistent trails do cause cloud formation.

Since the mid 90’s there has been growing popularity with regards to contrails in the “conspiracy” world – so much so that now they have been dubbed – Chemtrails.   Speculation on what chemtrails are is rife, from them being chemicals agents used by governments for mind control and the spreading of a virus.

Personally I am more concerned with the nature of commercial air traffic and the increasing effects this might have on weather systems.  The more people travel by air, the more persistent trails will occur in the sky, and the more cloud formation will occur and have a knock on effect with regards to weather systems, along with an effect on localised climate.

I recall when I was growing up that there were a lot less contrails in the sky.  There is a video the BBC have produced that illustrate the number of commercial flights over the UK – it’s quite incredible:

Flight Paths over Britian