Many of you are no doubt familiar with the animated version of Pickering's scale for determining seeing conditions. If you are not, Damien Peach created this animation, which can be found here:
For those of us who do not (or cannot) take a laptop out into the field when observing, CN moderator Olivier Biot has produced (with the permission of Damien Peach) a printable version of this scale that works very well in the field.