Smoke

When I saw such a view for the first time (in Syria), I thought it was bombing or shelling. I guess, most of the viewers would say it is fire. And you would be more-less right. What you see on the photo it's the effect of one of the conflict sides' efforts to destroy the wheat production in N Syria. This reminds me of medieval war strategies to "conquer by famine" i.e. cutting supply lines to besieged castles etc.