"Bill" wrote

Yesterday I was flying back from a weekend camping trip, and came up
behind my friend in his AA5. I started getting up close, and was
feeling the effect of the vortex off his right wingtip. I reached the
point that I had my ailerons deflected almost 50-60% to the right just
to stay level, when I suddenly SAW the vortex hitting my windshield!

I know if I heard this description I would say it was bull****. But I
saw it, as did my passengers. It was a tube of swirling distortion,
dropping down off his wingtip and then coming back to us.

You are the first I have ever heard describe this. Interesting. I would
think that there was a little moisture component along with the density and
diffraction, but perhaps not.

They say the late NASCAR race car driver, Dale Earnhart, could see "the
draft." His success at the highest speed tracks, where the draft was the
most important, would seem to make you think that he had something extra
working for him. Your account makes me give more credence to that legend,
now. Thanks for posting.
--
Jim in NC