"It's, uh, field burning...?"
I had never heard of such a thing, but remember, in summer of 1980, we were about to elect Ronnie Ray Gun president, and people my age grew up expecting to die- sooner rather than later- in a nuclear holocaust.
Now I suppose if you grew up or had spent some summers in the the Willamette Valley, you wouldn't think twice about it, and I know controlled burning is and long has been an important tool in agricultural management. Here, it's used mostly for hay and grass seed, two important products in this region; it gets rid of older waste that would shade and interfere with a second harvest's growth, and it kills a wide variety of pests and their eggs. The series of photos below were taken over a period of a few minutes.
The source of the fire is probably (from this perspective) below the street lamp; there's a mild northward wind, so the smoke column is leaning somewhat to the north. The view is eastward. As the column rises, it encounters a stronger northward wind and tips more strongly in that direction.
The smoke was yellower than the photo shows, but note the distinct change in texture and color (from light gray to bright white) right about where the wispy cirrus cloud goes behind the plume on the right. At that level, the smoke-filled ground-level air has been lofted high enough, and cooled enough adiabatically, that an actual cloud forms as moisture condenses.
Field burning used to be very, very common, like the wigwam burners used to be in the timber industry. However there was a terrible accident due to smoke from a burn in 1988:
Their plans ended forever when the smoke of a field burn blew across the highway on the afternoon of Aug. 3, 1988. Blinded by the smoke and in the smoky darkness the Rodewald’s van was hit from behind by an 18-wheeler and shoved beneath the vehicle in front of them. The family was burned alive in the fire that swept over the accident. In all, seven people were killed and 38 were injured in the 23-vehicle disaster that made headlines across the country. The only member of the du Aime-Rodewald family to survive that day was Kate’s son Wills, who had stayed home with his grandmother.Afterwards, field burning was heavily monitored, restricted and regulated. The annual acreage burnt has dropped from about 170,000 to about 50,000. A bill is currently wending its way through the Oregon Legislature to restrict it even more heavily, due to concerns regarding respiratory health; burning will be restricted to a few particular counties and a few particular crops. The annual acreage burnt is estimated to drop to 15,000, less than a tenth of that when I was an undergrad here in my little burg.
Like the wigwam burners, alternate methods of management have emerged, and I expect the days of controlled burns are numbered. I don't think that's a bad thing. But while I still get a bit of a nervous, startled, thrill when I unexpectedly catch a glimpse of a roiling mushroom cloud rising above the horizon, there is a wistfulness in me to think that these icons of late mid-valley summer will eventually vanish into the mist of history.