For an inexperienced flyer, it does look like smoke...
In a similar vein, my father overheard a passenger exclaim:"Look at all that snow!" when looking at nice fluffy, white clouds.
I saw something half a grade worse than that getting on to a VS flight SYD-HKG on Sunday. I thought at first it was some VS gimmick, perhaps a disco complete with dry ice "smoke" machine to welcome you on board .
First time I've seen it, but it's obviously more common than I thought.
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