Predicting balloon paths
Today at Brighton Astro Louis and Russ described their project launching a balloon from their back garden to some insane height (30km?). They recovered some great images, as you might imagine.
The part I was particular taken with is that you can predict the path of these things really well. They used https://predict.sondehub.org/ and launched during the best conditions they could, allowing for advanced notice to aviation.
The code behind it is a chunk of GPL licensed Python now, derived from a hunk of C from 10+ years ago. It pulls wind data from NOAA.
All very cool, and as you can see from the experience in the image above, amazingly accurate.