Contrails and clouds

Mishap I don't know anything about what effect contrails have on weather, but I do love them (for some reason you don't get them in the southern hemisphere, so they are still wondrously "new" to me).

We do get them in the Southern Hemisphere. When I lived in The Adelaide Hills in South Australia I saw them all the time, some were quite strange looking as in this photo link. Since moving to North Western Victoria I still see them every day and because the sky is often cloudless they are very obvious.

There are lots theories about. I would be interested to know what they are.

Earth Science Picture of the Day of a curved contrail and straight shadow.

Faye that's interesting, I definitely never saw one living in South Africa, I fell in love with them when we came to live in the UK. Perhaps it has to do with high flight paths? Will be on a mission now to find out!

Mishap - Wales happens to be having clear blue skies for a few days
Their appearance is affected by winds going at different speeds and in varying directions at high altitudes.
There is apparently a big debate on the effect of contrails (which are mainly water vapour - ie man made clouds) on climate. Is the net effect warming or cooling - we don't know yet.
When the volcanoashcloud closed the airports it was accompanied by clear weather and the skies over UK were pristine and bright blue. Usually a whitish film. I noticed the difference too when in NZ where the skies are a beautiful forget me not blue, very few contrails as it is not en route to anywhere. We get all the europe - n america stuff over us.

The whole chemtrail thing is quite bizarre. There is a video on Faye's link which blows the mind. I am not quite sure what it is trying to say - but it makes it sound sinister!

As to the contrails we are used to the one-directional ones, but what we are getting recently is very odd - not on a known route really.

We mainly get a lot of cloud in western europe because we are the first land all the water vapour that has formed over the Atlantic and is brought to us by the prevailing winds. The fact that skies were clear when planes were grounded after the ash cloud may have had more to do with weather patterns at the time (even GB gets clear skies sometimes) than lack of contrails. I suppose looking at pressure maps of the time might tell us a thing or two (clear skies are often associated with a patch of high pressure). Anything is pure speculation.

Sorry. First sentence not good, but I guess the idea is understandable

And the last sentence should be: anything else is pure speculation.

Of course the UK does not have clear skies ever Bags - I should have qualified "where I live" i.e. 50 miles N of London - we have a convergence of air traffic. That bound for London too low of course to leave con trails. But that passing to and from N Europe/ N America tends to go over us at higher altitudes. In great quantities. So clear blue skies here is very rare indeed.