(Click to enlarge)
This image was taken on 10/19/2017 at the Staunton River Star Party. Sky looked clear but as night went on I found it very difficult to understand guiding RMS (growing) and HFR of stars (also growing). I was able to look at a Satellite IR loop and noticed a thin area of moisture/clouds was moving over us very quickly. Conferring with visual obervers nearby confirmed my observations that seeing had gone out the window! At the start of the night I was getting an HFR of around 1.3 for my stars and by 11pm it had grown to 3.0! Pretty huge change quickly.