Why regular 'Irregularities' in Contrails?
Having seen many contrails over 'Wallasey', they all seem to have a regular continuous rhythm in their dispersal. Some have more than one 'frequency' present; with a quick pattern (every ~3 seconds) and a slower (maybe every mile) disturbance.
Are these patterns something to do with regular alterations of the servo elevator trims, or are they due to some natural phenomena ?
( Maybe they are caused by 'Vortex Shedding' ?)
If weather conditions improve, I will try to post some pictures.