I've revived the contrail pattern simulator on ContrailScience so the controls work again, and made it so it can be embedded in a post here. Note this is actually two different contrail simulators - the default shows two intersecting flight paths creating a grid, the other shows a racetrack contrail forming a pattern, you can toggle between them with the checkbox in the lower left. The key point that is being illustrated here is that contrails move across the sky - so when you see a contrail it's not actually the path the plane took - and it's often at a different angle to that path. It also shows that just two intersecting routes can create a grid across the whole sky - even if all the planes fly exactly along the same two routes. You can alter the simulator by dragging around the end points of the routes, and by adjusting the speed of the plane and the wind, as well as adjusting the wind direction. To embed it, used the code: [consim].[/consim] If you want to embed it on another website, the embed code is: Code: <iframe width=660px; height=660px; seamless; scrolling=no; src="https://www.metabunk.org/apps/racetrack_contrail_simulator/web-export/index.html"></iframe> And the full source code is attached. It uses the Processing framework.