Snow avalanches, landslides, and ice-rock avalanches produce heat and subsequently encounter different
flow regimes as they flow down the mountain. Snow avalanches, for instance, may transition from cold
powder-snow avalanches to warm, dense-flow avalanches, depending on snow temperature. Recently,
laboratory flow-experiments in a rotating drum revealed more details of the mechanisms driving the
temperature evolution in moving snow. Alongside measuring the detailed temperature evolution the
experiments allowed to reproduce associated flow regime transitions. Additionally to the known and
expected transitions it was possible to discover a new phenomenon, namely the thermal equilibrium of the
flow. At this steady flow state, the particle-gas interaction governs the temperature evolution. At sufficiently
low ambient temperatures, ambient air-cooling compensates frictional heating and thus prevents flow
regime transitions on a laboratory scale. Furthermore it turns out that the thermal energy balance of the
gravity-driven mixture can be described by a simple analytical model, only taking into account frictional
energy dissipation and heat exchange with the ambient medium. The model accurately captures the
measured temperature evolution and predicts the observed thermal equilibrium. The setup additionally
allows for a novel approach to measure and determine heat transfer coefficients and total shear stresses of
the flowing material solely based on measured temperatures. Moreover, the temperature and with it flow
regime evolution could be incorporated into new avalanche models calculating run-outs and impact
pressure - an important step for improving hazard assessment and mitigation measures.
