Milkweed Pods; Mother Nature's Wind Checkers
Understanding wind currents and thermals in hilly, broken terrain can often be incredibly frustrating. I've found that collecting and storing milkweed seed pods during the late summer has made me a better hunter in the bluff country that I hunt. These little feather like seed dispersers will float on the lightest of air currents and will show you what the wind is not only doing right at you're location but more importantly down range. I like to use the off season to float them in areas I intend to hunt.
I will bring my binoculars and release a handful of seeds and watch them dance through the timber, often they eliminate the site due to a current that eddy's and would give away my position to any approaching deer. Terrain breaks, patches of evergreens, open timber against thick understory all create their own unique air currents and without being able to "see" the wind you are really just hoping for the best.
Give it a try, I think you will be amazed at what the wind really does in your hunting area.