This is dust devil season across the Dakotas and western Minnesota. Dust devils happen on relatively calm and sunny days when a particular spot of ground heats up faster than the ground nearby. The air just above the warm spot is then heated more than the air around it. This warming of the air causes an expansion that makes the air lighter, so it rises and begins to rotate. If it rises fast enough, the column of air becomes narrower, causing the column to rotate faster. The rising air draws more hot air from nearby, feeding the circulation and making it self-sustaining.
From the top of the updraft, cooler air is displaced and this air slowly sinks around the edge of the vortex, keeping the system stable for several minutes. Dust devils are too small to be effected by the spin of the Earth, and so may spin either clockwise or counterclockwise.
