My ride to work takes me right under the flight path into Sydney airport, and the planes can be pretty low at times. On a really humid day - generally just before it is about to start bucketing down with rain - the low flying planes leave impressive dark grey vapour trails behind them.
The trails behind this aircraft are quite unimpressive compared to some that I have seen. Please excuse the fuzziness - I was riding along at about 25km/h and taking this photo one handed whilst trying to zoom in at the same time. I does my best.