Our neighbor's barn is full of tobacco, and now he's firing (fire-curing) the tobacco.
Inside the barn, sawdust is smoldering in trenches or a pit on the barn floor. A pile of sawdust stands ready between the barn and the highway. Hardwood slabs are usually burned along with the sawdust. If you are curious about the process, the University of Kentucky document, Harvesting, Curing, and Preparing Dark-Fired Tobacco for Market (pdf), is a good summary of the science of fire-curing.
Tonight the wind is carrying the smoke our way. We have some windows open this evening, and we can smell the smoke in the house. I don't enjoy the odor, so I closed the windows on the side that the breeze was coming through, and that helped.
Tobacco firing doesn't last too long. In a few weeks, this will be over. Before then, the wind will switch again and the smoke will blow somewhere else.
Related post: New Tobacco Barn
On the web: Image of the smoke-filled interior of a tobacco barn:1