Contrails :-(

[Stu]

There are times when I wonder why the skies are so poor around here, and then on a evening like Thursday I begin to see why.

It seems particularly bad at the moment, I guess because of the current atmospheric conditions (no conspiracy theories please!)

The joys of living a few miles from Heathrow.

There was an interesting article on the BBC website the other day about how alterations to flight paths could dramatically reduce the contrails which are produced. Would be good if something could be done to reduce them, I've always been fascinated by why sometimes you see a plane fly past producing no visible trail, whereas other times the trail is heavy and persists for a long time.

http://www.bbc.co.uk/news/science-environment-27907399

This explains how it is the times when the planes fly through very cold moist air which cause the trails. I also assume that when the atmosphere is very still at that altitude the trails do not get broken up so quickly.

Cheers,

Stu

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[D4N]

The military intentionally alter flight paths to avoid creating contrails but this is costly in both time and fuel, commercial airlines have no reason to do this.

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[DaveS]

Those are the sort of patterns I see only too frequently, living under the Heathrow flight path 

[DrRobin]

If you give up on astronomy you will have a great time photogrpahing contrails, they are really good pictures, especially the last one.

The BBC article mentioned was really good and gave a good explanation.  Contrails at high altitude are almost inevitable and unless there is instability at that altitude, tend to stay together, but just drift down wind.  Contrails at a lower level tend to look bigger, but disperse faster.

The problem is aircraft fly in 'corridors' so if you happen to be under one, it is always going to be a problem.  Air corridors (at 30,000 feet) always pass directly over airports and in days gone by airports were a primary location point.  The idea of routing aircraft to avoid contrails probably won't change aircraft over flying Heathrow at 30,000 feet.

Robin

[Kbramley]

I get these all the time in Lancashire, many a blue sky has been ruined with almost 100% coverage of dispersed contrails. Unfortunately I think for the foreseeable future airtravel will only increase. If only someone would invent a contrail filter

Keith

[Stu]

Thanks Robin. Fortunately there's no chance of giving up on astronomy, been doing it too long to pack in now.

I'd never really considered that the air corridors always pass over the airports. It makes sense of course and, as you say, means they will always be present over and around Heathrow.

Stu

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[Myopicus]

Yup, they're awful and inevitable.

A couple of my mates, upon seeing a contrail, loudly declare "chemical smog!" or something of the kind.  But, strangely, they seem happy enough to jump on a plane to India to 'find themselves'.