You can often see contrails of wingtips or even flaps in the right conditions. Contrary to what has been said above you don't need freezing conditions just a relative humidity of 100%.
So either you pump a bit more water and some nucleation points into the local atmosphere raising the RH above 100% - instant contrail. - or - You you change the pressure quickly enough (adiabatically) say at a wingtip or over a flap and you can sometimes raise a parcel of air that was just under 100% RH to just over 100% RH
If you land in low cloud or near fog conditions as a pax have a look at the air over the flaps, not unusually to see wisps of cloud forming.