Glen Berry turned me on to Atlas Glo Yarn 20 some years ago. Most of us have a ton of the stuff laying around from steelhead fishing. I keep all the short ends from tying egg balls in a 3X5" zipper type bag. The stuff is awesome!!! And one $3.99 bag will last about three years worth of wind testing as you only need to use a couple 1-2" fibers each time. I see the flo pink best, but nice thing is each person can choose the color their eye sees best. Can't do that with powder or LEDs.
A few strands will float for an hour it seems. And it is bright enough you can see what the wind is doing 20 yards away. There have been a lot of times I will think there is no way I can go after an animal in a particular spot. Send out a few bits of yarn and find out the wind changes 180 degrees five or ten yards of my location. No other compact wind detection system I know of can do that. Except maybe if you are hunting in a field of tansy gone to seed.
I still carry a puff bottle for quick reference. And I probably use it more than I should. But the puff bottle only gives you a small sample of what the wind is really doing. Try the fluffy yarn and I don't think you will be disappointed.