Con trails.

[cee-dee]

Oh dear, people will try to read all sorts of things in to things "in the sky".

http://news.sky.com/story/1340250/mystery-over-weird-plane-trail-photograph

All it was caused by was wind drift or the other aircraft crossing it.

Living on a hill and under several air routes including those from North America I see con trails all the time and sometimes the long-lived ones (some disappear quickly) end up looking quite strange.

[otherego]

I'd also lean towards an artifact of the high level winds, noticeable after the aircraft's passage. I suppose it could also have been "finger trouble" ("Hey, what's it doing in heading mode?"), but that seems less probable at that stage of the flight.

From the article you linked to - I particularly liked:

Somebody said a UFO had been spotted recently in the area and the pilot had tried to avoid it

She did say that she liked the sound of that, and not that she believed it for one moment. More worrying was her assertion about there being no wind. True at ground level, perhaps.

A shame the reality is always so dull.

[upthecreekyetagain]

If it was the wind that shifted the contrail, rather than an actual change in course of the aircraft, I would have expected the vapour trail to have been dispersed and appear wider in those areas affected.

[cee-dee]

If you live in a place where many air routes pass and/or cross, over time you'll see some really strange effects depending on the temperature and the wind drift.

My explanation of "wind drift" as against "wind" is when the air is relatively still with little apparent wind but the air imperceptibly "drifts".

With con trails, sometimes an aircraft leaves a trail which doesn't last very long at all, you can see the aircraft leaving the trail but the trail's gone after half a minute. Another time, you can see an aircraft approaching at distance, see the trail it's left, watch it approach, pass over and fade in to the distance and the trail will still be there.

With "wind", the trail will be dispersed, with "wind drift", the trail will be displaced but the trail be virtually intact.

At 450 - 500 MPH a change of direction as shown in the pic over that relatively short distance to resume not far off a straight line would be a little difficult to say the least.

[bankhaunter]

Many people don't realise just how dynamic the upper air actually is, they assume whatever is happening at ground level is the same all the way up.

I have seen clouds circling which would have led to interesting contrails.

[cee-dee]

I was watching intercontinental planes flying over this morning. The con trails they were leaving were only lasting about 30 seconds.

However, a con trail much further North of here lasted over 10 minutes and you could see that at the flight level the intercontinental planes were at, there was no wind because the trails lasted as a straight line as did the long lasting one which was above the fluffy White clouds which were also floating about.

[saasher2012]

Please may I ask what does con trail stand for?

[bankhaunter]

Condensation trail, water vapour given off as fuel is burned.

How long it lingers, how it spreads etc. depends on the atmospheric conditions at the height the aeroplane is flying.

There are those who are convinced that the ones which linger are actually chemicals being sprayed on us for various reasons varying from climate control to population reduction.

The fact that if that was true it obviously doesn't work seems to completely escape the conspiracy theorists.

[cee-dee]

They call those chem trails, nutters.

http://en.wikipedia.org/wiki/Chemtrail_conspiracy_theory

[cee-dee]

Here's a B & W pic of some long lasting con trails:-

The pic was taken during the Battle of Britain, 1940!

[saasher2012]

Thank you, that's where I was confused I kept thinking vapour!.

[cee-dee]

They are also called "Vapour trails" but the "modern" way is to abbreviate it to "con-trails".

[bankhaunter]

It's also possible for water vapour in the air, to condense sufficiently to be visible from changes in pressure as it passes over parts of the aircraft.

You can see it forming from the wingtip vortices in this video, also briefly a couple of example where it covers the entire upper surface.

http://www.youtube.com/watch?v=NKQCOBGSQeE

[upthecreekyetagain]

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@saasher2012 wrote:
Please may I ask what does con trail stand for?

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A con trail is the track a convict leaves escaping from prison - a contrail is the trail of water vapour or ice crystals formed by a high flying aircraft 🙂

[saasher2012]

Couldn't use a police dog for one of those then? lol.