Stagnation conditions are characterized by synoptic pressure gradients so weak that they have little or no effect on air flow near the ground. This flow and the turbulence accompanying it are driven mostly by surface heat flux inducing buoyancy, which interacts with terrain slopes. The resulting flows and diffusion patterns created by these flows are as varied as are topographies. Short-term diffusion is also strongly affected by uneven surface heating or cooling induced by various sun azimuths and elevations, uneven surface cover, soil type and moisture, and by uneven cloud shadowing. The endless possibilities makes the task of predicting 'worst case' concentrations from a particular source in a particular place seem almost impossible, but there is hope for useful predictions for time averaged impacts from arrays of many small sources, such as woodstoves. This is the primary focus of the experiment described in the paper.