Contrails- You're Not Welcome Back!

[Summer of 95]

For the first time in my life, I have experienced 6 consecutive days when no planes flew over my head and I honestly believe it made a major difference to the weather I observed. And enabled me to experience the natural weather my forebears would have enjoyed prior to the War.

When I first heard of the flight ban last Thursday, immediately my first thought was to check the sky. Sure enough, in between the small patches of cumulus floating around were bright, crystal blue skies, with no sign of any high cloud at any point despite the presence of the ash. The sun seemed unusually strong considering it was April and under 15C- it was easily short-sleeve weather and the morning's cloud had burnt off hours earlier than forecast.

Friday, much of the same; the North Sea cloud had mostly gone by 10am (normally it often persists till beyond midday in June) and there were the azure, unblemished skies above. Again not a sliver of high cloud.

Saturday- this was the day that truly made me want to give thanks for the Norse gods for giving us Eyjafjallajokull. Absolutely cloudless (not just Cu, no high cloud was seen all day) from dawn till dusk; something that in recent years has hardly ever been achieved outside the December to March period. Especially at weekends (compare the previous Saturday which was ruined by constant cloud formations above 20,000ft, which dimmed the sun to such an extent that it struggled to cast shadows. I now believe this to have been 100% aircraft-caused and that we would have reached 21C over much of the UK without it.) Even the otherwise perfect months of April 2007 and July 2006 had several days when patches of high cloudlike structures floated around, and several with obvious aircraft pollution turning the sky more white than blue.

Sunday- morning was like Saturday; some cloud appeared in the afternoon but it was low Sc/Cu, yet again I saw no clouds above 10,000ft.

Monday- with a weak front over us the cloud did persist more, but even then it thinned from time to time (yes, perfect blue above again).

Tuesday- with no cloud overnight it was -0.5C at 5am, and +12C at midday. No change of airmass, frontal passage or wind change caused that, just the Sun being able to shine unimpeded by any haze thrown out by planes. The day when I realised what they say about contrails reducing the diurnal range was undoubtedly true. Not a single high cloud seen all day yet again.

Wednesday- Judgement Day.

5.30am- as clear as the day before but the temperature was not as low (the forecasts suggested it would be); it was +1.5C and despite a few patches of frost I didn't need to defrost the car like yesterday. The first sign of something amiss? (Still no high cloud visible then). Heard that planes had started again during the night.

Morning- The sun came up, but didn't seem to be able to do its warming quite as well, even by noon it was barely 10C. That's 4C less range than yesterday despite seemingly identical conditions.

3pm- Like the Spanish Armada coming back for a rematch; the menace reappeared low on the S and SW horizons. Those tell-tale lines of pseudo-cirrostratus with a few fresh yet-to-expand lines between them. Luckily the planes I could by now see flying above only produced short-lived trails that went in a few minutes- perhaps by pure luck I was under a pocket of drier upper air.

4pm- The Armada is fast approaching, though as they rose the aircraft clouds visibly thinned to the point where they didn't weaken the sun much, but did turn the once-azure skies the colour of an old blue T-shirt that's had too many washes. And a few drops of bleach thrown on it. However on closer inspection I noticed the thinning trails were turning into something that could quite easily be mistaken for natural cirrus, except that they were still in obvious lines and I had watched them form. Seeing this made me realise I've vastly underestimated just how much high cloud is unnatural; when I've seen these formations before I've usually thought them to be natural hazy stuff. Still however those plannes overhead onlymake short-lived trails. Also I now realise that much of the aircraft pollution doesn't form where I can see it, but hundreds of miles away.

5pm- The sky to the N and NW is still blue, but the haze has now reached halfway across it. Although very thin more than 20deg high it's easily visible, and the sun starts to sink into the thicker stuff. Feel cheated, robbed and really guilty about having taken so many planes in the past. Seeing the sky violated in this way this afternoon made me realise just how many clear days we are being deprived of.

Come back ash, and give us an aircraft-pollution-free summer!

[Pennine Ten Foot Drifts]

Absolutely, the sky these last few days has been wonderful. Ah well, we all made this bed so I guess we gotta lie in it.

[Gray-Wolf]

Don't forget that far off 'rumble' that is constantly there! I know we hear them go overhead and fade but it's the distant thunder that I can live without (and the amplified bird song!!!)

[Summer of 95]

Absolutely, the sky these last few days has been wonderful. Ah well, we all made this bed so I guess we gotta lie in it.

Until we fall out with a bang- like the next Icelandic volcanic bang that's hopefully round the corner....

[johnholmes]

For the first time in my life, I have experienced 6 consecutive days when no planes flew over my head and I honestly believe it made a major difference to the weather I observed. And enabled me to experience the natural weather my forebears would have enjoyed prior to the War.

When I first heard of the flight ban last Thursday, immediately my first thought was to check the sky. Sure enough, in between the small patches of cumulus floating around were bright, crystal blue skies, with no sign of any high cloud at any point despite the presence of the ash. The sun seemed unusually strong considering it was April and under 15C- it was easily short-sleeve weather and the morning's cloud had burnt off hours earlier than forecast.

Friday, much of the same; the North Sea cloud had mostly gone by 10am (normally it often persists till beyond midday in June) and there were the azure, unblemished skies above. Again not a sliver of high cloud.

Saturday- this was the day that truly made me want to give thanks for the Norse gods for giving us Eyjafjallajokull. Absolutely cloudless (not just Cu, no high cloud was seen all day) from dawn till dusk; something that in recent years has hardly ever been achieved outside the December to March period. Especially at weekends (compare the previous Saturday which was ruined by constant cloud formations above 20,000ft, which dimmed the sun to such an extent that it struggled to cast shadows. I now believe this to have been 100% aircraft-caused and that we would have reached 21C over much of the UK without it.) Even the otherwise perfect months of April 2007 and July 2006 had several days when patches of high cloudlike structures floated around, and several with obvious aircraft pollution turning the sky more white than blue.

Sunday- morning was like Saturday; some cloud appeared in the afternoon but it was low Sc/Cu, yet again I saw no clouds above 10,000ft.

Monday- with a weak front over us the cloud did persist more, but even then it thinned from time to time (yes, perfect blue above again).

Tuesday- with no cloud overnight it was -0.5C at 5am, and +12C at midday. No change of airmass, frontal passage or wind change caused that, just the Sun being able to shine unimpeded by any haze thrown out by planes. The day when I realised what they say about contrails reducing the diurnal range was undoubtedly true. Not a single high cloud seen all day yet again.

Wednesday- Judgement Day.

5.30am- as clear as the day before but the temperature was not as low (the forecasts suggested it would be); it was +1.5C and despite a few patches of frost I didn't need to defrost the car like yesterday. The first sign of something amiss? (Still no high cloud visible then). Heard that planes had started again during the night.

Morning- The sun came up, but didn't seem to be able to do its warming quite as well, even by noon it was barely 10C. That's 4C less range than yesterday despite seemingly identical conditions.

3pm- Like the Spanish Armada coming back for a rematch; the menace reappeared low on the S and SW horizons. Those tell-tale lines of pseudo-cirrostratus with a few fresh yet-to-expand lines between them. Luckily the planes I could by now see flying above only produced short-lived trails that went in a few minutes- perhaps by pure luck I was under a pocket of drier upper air.

4pm- The Armada is fast approaching, though as they rose the aircraft clouds visibly thinned to the point where they didn't weaken the sun much, but did turn the once-azure skies the colour of an old blue T-shirt that's had too many washes. And a few drops of bleach thrown on it. However on closer inspection I noticed the thinning trails were turning into something that could quite easily be mistaken for natural cirrus, except that they were still in obvious lines and I had watched them form. Seeing this made me realise I've vastly underestimated just how much high cloud is unnatural; when I've seen these formations before I've usually thought them to be natural hazy stuff. Still however those plannes overhead onlymake short-lived trails. Also I now realise that much of the aircraft pollution doesn't form where I can see it, but hundreds of miles away.

5pm- The sky to the N and NW is still blue, but the haze has now reached halfway across it. Although very thin more than 20deg high it's easily visible, and the sun starts to sink into the thicker stuff. Feel cheated, robbed and really guilty about having taken so many planes in the past. Seeing the sky violated in this way this afternoon made me realise just how many clear days we are being deprived of.

Come back ash, and give us an aircraft-pollution-free summer!

I have to say this is one of the most biased and unsubstantiated posts I've ever read on NW. Contrails only appear in the sky when the air temperature is sufficiently cold for that to occur. One can find this out quite easily on a t-phi or skew-t diagram. As to the sky being hazy due to aircraft pollutants I'm afraid I will need much more scientific evidence before I believe there is anything in your idea of that.

Forgive me for being so blunt in my response but as a scientist I need proof not somewhat muddled observations on supposed air clarity.

[laserguy]

Absolutely, the sky these last few days has been wonderful. Ah well, we all made this bed so I guess we gotta lie in it.

Don't look at me - I've never flown in my life,and have no intention to (how odd for one of those AGW deniers)!

[Crepuscular Ray]

I have to say this is one of the most biased and unsubstantiated posts I've ever read on NW. Contrails only appear in the sky when the air temperature is sufficiently cold for that to occur. One can find this out quite easily on a t-phi or skew-t diagram. As to the sky being hazy due to aircraft pollutants I'm afraid I will need much more scientific evidence before I believe there is anything in your idea of that.

Forgive me for being so blunt in my response but as a scientist I need proof not somewhat muddled observations on supposed air clarity.

John, I hesitate to question what you say because you have far greater knowledge in the area than most of us here, especially non-experts like me, but wasn't there a report after the events of September 2001 in the USA of a noticeable diminution in - for lack of a better term (and that's me not remembering the technical term, not a lack of precision on the part of the people who wrote the report) - high-level haze? It's probably just a subjective observation or a coincidence, but over the last few nights (well, the cloud-free ones anyway), I've seen more stars than I have for some years (as in, I've seen about 20, rather than the normal 4). As a complete non-physicist, I'd like to ask whether even if the emissions from aeroplanes don't cause contrails (because the atmospheric conditions aren't right), might the water molecules still lurk, cumulatively causing the aforementioned (unscientific) haze?

Edited April 21, 2010 by crepuscular ray

[MAF]

well i have asked the question before. i wonder what the pollution levels will be for the last week in London. i realise that there are factors which may have been conducive for low pollution anyway, but from my experience of living in London (all my life) i have to say that my usual view across the thames towards the north has rarely been clearer. no high level haze at all. as i say it could be totally down to weather conditions and nothing to do with lack of aircraft in the air. who knows :lol:

[johnholmes]

Obviously with no aircraft flying over such a large area then the instances when contrails would occur because of weather conditions will be free of contrails but that is all.

On the subject of air pollution, jet exhausts, then that too must have an effect.

My main disagreement was over the idea that contrails have a LARGE effect on the cloud cover. Only when there is a front or low affecting any area will these combine with the already present cloud sheets and could perhaps add 5% to the total cover. At other times when we see contrails their effect, according to most meteorologists, is negligible. I accept that air pollution near busy airports and close by the touch down points at busy airports is another matter.

[noggin]

Don't look at me - I've never flown in my life,and have no intention to (how odd for one of those AGW deniers)!

Me, too! No force on this Earth would get me on to a plane. How can a great lump of metal stay in the sky? My late neighbour was an engineer at Rolls Royce/BAE and we'd spend hours having chinwags over the fence about it, but even he couldn't convince me that it's safe!

....and let's not go anywhere near airlines and stranded passengers wanting compensation. If the taxpayer ends up baling them out then I shall blow a gasket! I can't afford holidays myself and am not enamoured with the possibility of having to compensate others for their "misfortune".

The clear blue skies have been beautiful, now it's back to dozens of darned contrails spoiling it again.

I am also hoping that this whole business will serve as a salutary lesson to the arrogance of those who seem to think they can do whatever they want without so much as a by-your-leave from this old Earth of ours. Mother Nature is in charge...not us.

I will now step down from my soap-box!

Oh, and I'm sick to death of it being on the news all the time, too!

Edited April 22, 2010 by noggin

[osmposm]

Obviously with no aircraft flying over such a large area then the instances when contrails would occur because of weather conditions will be free of contrails but that is all.......My main disagreement was over the idea that contrails have a LARGE effect on the cloud cover. Only when there is a front or low affecting any area will these combine with the already present cloud sheets and could perhaps add 5% to the total cover. At other times when we see contrails their effect, according to most meteorologists, is negligible. I accept that air pollution near busy airports and close by the touch down points at busy airports is another matter.

John, my only problem with that is that I often watch high-altitude contrails forming, and slowly expanding out to a thinner, but much wider strip.....and staying as a vaguely linear area of cloud as the airmass moves across the sky. In busy air-lanes they are joined and crossed by other trails, and so on. That is my frequent observation, a high-level patchwork of streaks of cloud. It doesn't always happen, sometimes the trails just disappear; but often they do not.

I am not a meteorogist or scientist of any kind, and it may be that what I have observed (and what I, like '95, joyfully didn't observe during the flight ban) doesn't make scientific sense. But as I look up into the mainly blue sky now, I see that patchwork of streaky bits of hazy cloud that oddly (if they are natural) lie at various intersecting angles to each other. And I, too, suspect there is something in it.

[PersianPaladin]

John, my only problem with that is that I often watch high-altitude contrails forming, and slowly expanding out to a thinner, but much wider strip.....and staying as a vaguely linear area of cloud as the airmass moves across the sky. In busy air-lanes they are joined and crossed by other trails, and so on. That is my frequent observation, a high-level patchwork of streaks of cloud. It doesn't always happen, sometimes the trails just disappear; but often they do not.

I am not a meteorogist or scientist of any kind, and it may be that what I have observed (and what I, like '95, joyfully didn't observe during the flight ban) doesn't make scientific sense. But as I look up into the mainly blue sky now, I see that patchwork of streaky bits of hazy cloud that oddly (if they are natural) lie at various intersecting angles to each other. And I, too, suspect there is something in it.

I agree with that.

Depending on the conditions and the frequency of airtraffic; contrails can pretty much merge into more dense cirro-stratus clouds albeit they won't give the degree of cloud cover that an encroaching warm-front will.

[johnholmes]

hi As and others

Bit busy with pond problems at the mo but will try and get something together over the next day or two, regarding contrails, how a forecaster predicts them and how they can disperse or grow as you suggest.

For starters today after a quick look at upper air plots suggests only aircraft above about 30 maybe 35000ft will 'trail' and some of that will be what forecasters call persistent. By that they mean it will take some time, sometimes several hours for them to dissipate, from about 30000ft upwards today and below 35000ft they are what we could call non persistent. The type, when you look at the sky and see an aircraft and the trail disappears almost as soon as its made.

have a look at the infra red sat piccs, they seem to suggest quite a lot of trails from the Low Countries towards Lincs but only a few south of there?

will come back as I say when time permits.