What was this stream of aerosol I saw?
I flew on an Airbus A380 last week, sitting over the wing, and from during take-off from LHR until late in the ascent, inboard of at least one of the engines, about where the writing is, there was a thick but tight stream of vapour coming from just in front of and below the leading edge to near the trailing edge where it dissipated. It was as if there was a hose playing upwards hidden just out of sight. It wasn't all along the wing, just this one stream. It was as if there were a fuel leak from the inner engine spraying upwards. But the stream disappeared at some point when we went through clouds. I asked one of the cabin what it was and they did not know.
I also saw it during the landing at LHR on the return trip; I did not see it when landing at DFW.
FWIW I was looking out over the wing to see how it flexed. Most impressive.