Shaking and white trails on take-off

[JohnnyRocket]

I have often noticed that just after a plane takes off there is a couple of seconds of vibration. The aircraft shakes and then it stops.

What is this shaking or is it simply something to do with the undercarriage?

Also, why are white trails sometimes seen coming from the wingtips on takeoff and landing? What causes this phenomenon and why is it just at these times?

[Groundloop]

Also, why are white trails sometimes seen coming from the wingtips on takeoff and landing? What causes this phenomenon and why is it just at these times?

They are caused by water vapour in the atmosphere condensing out in the low pressure air in the wingtip vortex. You only see them on days when there is high humidity. The lower pressure air cannot hold as much moisture so it condenses out into visible vapour. Sometimes the whole upper wing surface can be covered in vapour on really damp days.

[sir.pratt]

18 x 300kg wheels suddenly spinning free of the earth, and the bottom of the plane opening up to accept said wheels causes buffetting (read: shaking)

[BOAC]

Johnny - white trails sorted. Check out this thread for the rest.