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.