Bloggers Avi and Rachel Abrams, who run an eclectic blog called Dark Roasted Blend, recently posted a collection of photos that I'm sure anyone interested in aviation would enjoy. Drawn from various sources, the photos are of jet contrails, vortices, condensation clouds, and similar aviation eye candy.
Go and have a look at "Jets & Clouds" Effects. Then, as long as you're there, click on the airplanes category label near the top of the page. Lots of cool stuff to look at. Enjoy.
(And no, I don't know why they named their blog Dark Roasted Blend.)
[Photo Source]