Other types of fire whirls continue to challenge our understanding, particularly those that occuroff source or are nonsteady. Certainly the velocity and temperature fields within these whirls maydiffer, but exactly how remains to be seen. A reliable method for generating these whirls within thelaboratory, as well as detailed measurements of their structures, would be very beneficial to ourunderstanding. Even stationary fire whirls over a fuel source precess around the source, causingthem to move and wander, triggering unknown effects to the structure of the fire whirl, especiallywhen they are near the limits of their stability (e.g., fuel rich or high swirl). The effects of the levelof circulation (e.g., Rossby number) on the structure of fire whirls are not well known, as mostexperiments have been performed only under a limited range of circulations and scales.