Sometimes it looks as if an aircraft has crashed with great clouds of billowing black smoke drifting away,fading and blending into the distant clouds. A farmer friend said the mucky ones are when old agricultural fleece is being disposed of and the smoke from those fires makes you think a couple of foam mattresses and a three piece suite are being burnt, having been started with a liberal splash of diesel.
This one looks like organic material with that brown tinge in the smoke and you can pretty well guarantee that someone five miles downwind will be saying, 'who's got that stinking fire?' and they'll be blaming a near neighbour.