There are lots of examples of vortices in nature. Tornados, for example. And if you watch an aircraft take off from Heathrow on a damp day, you’ll see a vapour trail spinning from the tip of the wing, which is the wing tip vortex we’re talking about. You see it on a racing car, coming off the rear wing on a wet day, when the humidity is such that it causes the flow to condense into a vapour trail.
