"We looked at the ratio between convection and surface turbulence to find the sweet spot where there is enough updraft to overcome the low level wind and turbulence," said Williams. "And on Mars, where we think the process that creates a vortex is more easily disrupted by frictional dissipation - turbulence and wind at the surface - you need twice as much convective updraft as you do on Earth."
PHOTO: Dust Devil Spotted Whirling Across Mars
This conclusion was reached after studying meteorological data from Australian dust devils and comparing that with observations by NASA's Viking Lander mission. The researchers were able to create a 1-dimensional "planetary boundary layer model" that could identify the ideal conditions for dust devil formation in the Martian atmosphere and, as it turned out, for a dust devil to form on Mars, more powerful convection currents were needed at the surface layers.
This study is much more than just a curiosity about Martian dust devils, however. Considering the Martian atmosphere is, on average, less than one percent the pressure of Earth's atmosphere (at sea level), dust has a significant impact on the planet's climate. As dust devils provide a mechanism for kicking substantial quantities of dust into Mars' atmosphere, they could act as a global climate control of sorts.
ANALYSIS: Weird Kind of Dust Found in Mars' Atmosphere
"The Martian air is so thin, dust has a greater effect on energy transfers in the atmosphere and on the surface than it does in Earth's thick atmosphere," said Nair.
During the day, dust in the Martian air reduces the amount of sunlight that would otherwise heat the surface, but during night, the atmospheric dust emits long-wave radiation, warming the surface. Therefore, understanding how this dusty haze is transported into the thin Mars air via dust devil activity will aid Mars climate models, potentially helping us fit another piece of the Mars climate puzzle.
Source: University of Alabama in Huntsville