When
3:30 p.m., April 22, 2008
Where
Kuiper Space Sciences Building 308
Ralph D. Lorenz, from Johns Hopkins University, Applied Physics Laboratory, is the scheduled speaker.
Abstract:
The action of wind on a planetary surface can take many forms, notably the formation of sand dunes. Cassini Radar mapping of Titan's surface has revealed massive fields of organic sand dunes covering some 20% of that body. Remarkably, seasonal changes in Titan's winds seem to influence Titan's rotation in a measurable way, indicating that Titan's ice crust is decoupled from its core by an internal water ocean. Titan's dunes are almost all of the linear type, like those in the Sahara and Namib deserts. I will review the surprising discovery and characteristics of Titan's dunes.
The mechanical coupling of energy from the atmosphere to the surface depends substantially on the density of the atmosphere. This effect is illustrated in decades of wind tunnel studies of aeolian transport, as well as in experiments on wave generation in water and kerosene (as a Titan analog) performed by the author in the NASA Mars Wind Tunnel.
Wind-driven transport of surface material takes its most extreme form in the moving rocks of Racetrack Playa, Death Valley National Park. I will report some ongoing theoretical studies and observations on this remarkable phenomenon. Finally, heat from the sun is typically the ultimate energy source for wind, and this thermodynamic association is graphically clear in desert dust devils, dry convective vortices driven by strong solar heating. I describe the application of novel technologies such as wireless sensor networks and thermal imaging to studying these phenomena in Southern Arizona.
Abstract:
The action of wind on a planetary surface can take many forms, notably the formation of sand dunes. Cassini Radar mapping of Titan's surface has revealed massive fields of organic sand dunes covering some 20% of that body. Remarkably, seasonal changes in Titan's winds seem to influence Titan's rotation in a measurable way, indicating that Titan's ice crust is decoupled from its core by an internal water ocean. Titan's dunes are almost all of the linear type, like those in the Sahara and Namib deserts. I will review the surprising discovery and characteristics of Titan's dunes.
The mechanical coupling of energy from the atmosphere to the surface depends substantially on the density of the atmosphere. This effect is illustrated in decades of wind tunnel studies of aeolian transport, as well as in experiments on wave generation in water and kerosene (as a Titan analog) performed by the author in the NASA Mars Wind Tunnel.
Wind-driven transport of surface material takes its most extreme form in the moving rocks of Racetrack Playa, Death Valley National Park. I will report some ongoing theoretical studies and observations on this remarkable phenomenon. Finally, heat from the sun is typically the ultimate energy source for wind, and this thermodynamic association is graphically clear in desert dust devils, dry convective vortices driven by strong solar heating. I describe the application of novel technologies such as wireless sensor networks and thermal imaging to studying these phenomena in Southern Arizona.
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