A SIMPLE THERMODYNAMICAL THEORY FOR DUST DEVILS

Based on the heat engine framework, a simple scaling theory for dust d evils is proposed and compared to observations. This theory provides a simple physical interpretation for many of the observed characteristi cs of dust devils. In particular, it predicts the potential intensity and the diurnal variation of dust devil occurrence. It also predicts t hat the intensity of dust devils depends on the product of two thermod ynamic efficiencies, corresponding respectively to vertical and horizo ntal temperature gradients.