Effects of temperature and humidity upon the transport of sedimentary particles by wind



Wind tunnel simulations of aeolian transport carried out over a range in mean temperature between 32 °C and −9 °C suggest that cold airflows support higher mass transport rates (Q) than very warm air. The magnitude of this increase is larger than expected, so that analytical and semi-empirical models underestimate Q. Extrapolation of the results suggests that, at −40 °C, as for example in the dry valleys of Antarctica in winter, Q may be as much as 70% higher than for the equivalent wind speed in hot deserts at air temperatures of 40 °C. Temperature-dependent changes in air density and turbulence contribute to this result. The decreased tension of water adsorbed onto particle surfaces at low temperatures is postulated to reduce interparticle cohesion and, thus, to increase the elasticity of particle impacts on cold beds. Definition of the roles that temperature and humidity play in aeolian transport is relevant to studies of palaeoenvironmental reconstruction and extraterrestrial (or planetary) geology. Investigation of present-day, cold climate features and of climate change effects also requires knowledge of these fundamental relations.