Unusual contrail
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Unusual contrail
During 60+ years of watchingg the skies I thought I'd seen most things but a contrail this morning had me puzzled. There was a stable anticyclone over the UK and contrails from many other aircraft at the time were "straight and true" until they dissipated. However, one commercial B747-400 produced a very distorted trail as it flew westbound over Woodley at around FL360. Piccy here:
Contrail from commercial B744 in stable air on 19 Jan 2011. All other trails at the time were straight. :: Contrail-19_1_11.jpg :: Fotopic.Net
At about the same time, an eastbound flight produced a normal trail. Any clues anyone?
Contrail from commercial B744 in stable air on 19 Jan 2011. All other trails at the time were straight. :: Contrail-19_1_11.jpg :: Fotopic.Net
At about the same time, an eastbound flight produced a normal trail. Any clues anyone?
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From the "S" shape size ( a few miles if not 10s of miles) this is woud indicate a wave , so I would guess the resurgence of a (single) mountain wave effect . Stable before, stable after, but if another aircrfat would pass at this altude some minutes later and conming in the top of the wave effect you would see the same.
Not sure this is this is the correct explanation, but one that come to mind . As a glider pilot, I experience and use this wave effect often , althought it would be unusual indeed above the UK.
Not sure this is this is the correct explanation, but one that come to mind . As a glider pilot, I experience and use this wave effect often , althought it would be unusual indeed above the UK.
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I think about another ACFT crossing the path few minutes earlier, 1 or 2 thousands feet above.
The contrail disapears, but the wake turbulence remains and goes down. Space between right and left vortex increases, hence the weird contrail below.
The contrail disapears, but the wake turbulence remains and goes down. Space between right and left vortex increases, hence the weird contrail below.
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The 300hPa wind is shown as being northerly today.Around 90k running from the west coast of Norway towards east Anglia.The High is well established at normal cruise altitudes elswhere over UK.
Well as today seems aday for contrail spotting west of London I was tempted to mention one i saw around 1330 UK time a spectacular arc spreading from way out to the east in a long sweepign curve headed down towards Sotuhampton and passing right over my back garden in Camberley
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Probably nothign unusual although it did appear to be coming from biggin/dover direction and seemed a fairly large course change but in contrast to one mentioned at the start of this thread the complete opposite -a thick brilliant white arc across the sky that must have been something like 30 odd miles long as stable as though it had been painted on the blue-lovely sight
PB
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Probably nothign unusual although it did appear to be coming from biggin/dover direction and seemed a fairly large course change but in contrast to one mentioned at the start of this thread the complete opposite -a thick brilliant white arc across the sky that must have been something like 30 odd miles long as stable as though it had been painted on the blue-lovely sight
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From uk.sci.weather
Folks,
Posted this yesterday on uk.sci.weather:
Glancing up into the blue a few minutes ago a Boeing 777 from Amsterdam to Lima was flying about 5 km north of me in the middle of Bristol. It was cruising at 32 000 feet (9754 m) and 889 kmh (480 kts, 552 mph- thanks flightradar24).
The contrail didn't hang around long before evaporating, about 40-50 secs, but as it was passing it developed a distinctive wave pattern. The wavelength (both north and south lateral displacement) was about 2 km (approx 8 secs flying time). There were four displacements (2 full wavelengths) visible before the contrail had evaporated and they were growing still as they vanished, the largest amplitude being about 1/3 wide as long. The contrail continued after these waves in a straight line, with the later amplitude not growing as much as when I first saw the 'wobble'.
Anyone like to theorise what sort of phenomena causes lateral waves of 2 km wavelength in the what I assume today is the stratosphere? The plane could have been at the tropopause, although, in my ignorance, unaware of any sort of boundary condition that would cause this. My only regret is not seeing it develop before, just catching it at what I assume is a maximum.
Follow on posts said that the tropopause was probably above the aircraft.
I saw this at 1115 GMT, could I ask what time it was seen at Woodley and Lightwater? Totally agree that it was unique, at least in my experience, probably a gravity wave, but the fact it's crossed southern England is of more interest. Would like to dig into this a little further if anyone has further information.
Cheers,
David.
Posted this yesterday on uk.sci.weather:
Glancing up into the blue a few minutes ago a Boeing 777 from Amsterdam to Lima was flying about 5 km north of me in the middle of Bristol. It was cruising at 32 000 feet (9754 m) and 889 kmh (480 kts, 552 mph- thanks flightradar24).
The contrail didn't hang around long before evaporating, about 40-50 secs, but as it was passing it developed a distinctive wave pattern. The wavelength (both north and south lateral displacement) was about 2 km (approx 8 secs flying time). There were four displacements (2 full wavelengths) visible before the contrail had evaporated and they were growing still as they vanished, the largest amplitude being about 1/3 wide as long. The contrail continued after these waves in a straight line, with the later amplitude not growing as much as when I first saw the 'wobble'.
Anyone like to theorise what sort of phenomena causes lateral waves of 2 km wavelength in the what I assume today is the stratosphere? The plane could have been at the tropopause, although, in my ignorance, unaware of any sort of boundary condition that would cause this. My only regret is not seeing it develop before, just catching it at what I assume is a maximum.
Follow on posts said that the tropopause was probably above the aircraft.
I saw this at 1115 GMT, could I ask what time it was seen at Woodley and Lightwater? Totally agree that it was unique, at least in my experience, probably a gravity wave, but the fact it's crossed southern England is of more interest. Would like to dig into this a little further if anyone has further information.
Cheers,
David.
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The pic referred to in my original posting was taken at 08.30. Other aircraft trailing at the time were showing distinctly straight trails so whatever caused the distorted trail must have been in a narrow window.
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Just to say that similarly to yourself, have been watching contrails for many years and have never seen one like this. Any comments on its development? I saw pretty much what is in the photo and didn't see it before it got to that stage. Also had a series of contemporaneous flights further north with no deviation. Also, a plane at the same FL came past 23 mins later with no sign of 'the wave'.
Uncertain of other flights North-South that could have caused a down-draught (as theorised in a previous post), but the similarity of the shape of the wave for us both (wish I had got the camera) makes we wonder if it's some sort of gravity wave moving east-west- but what causes such a lateral displacement, I have no idea.
Cheers,
David.
Uncertain of other flights North-South that could have caused a down-draught (as theorised in a previous post), but the similarity of the shape of the wave for us both (wish I had got the camera) makes we wonder if it's some sort of gravity wave moving east-west- but what causes such a lateral displacement, I have no idea.
Cheers,
David.