Have you ever seen the mesmerizing hexagonal shapes that cover salt deserts like Badwater Basin in California or Salar de Uyuni in Bolivia? Scientists and travelers have been baffled by these strange patterns for years - but a new study has finally cracked the code.
Previous theories suggested that the ridged cells were formed due to cracks in the briny surface as it dried out or expanded. However, none of these explanations accounted for the uniformity of size and arrangement of these cells. Now, an international team of researchers has proposed a new theory based on a mix of field research and numerical simulations. They suggest that contrasting concentrations of salt-water solutions circulating in donut-shaped currents could be responsible for creating these stunning hexagonal shapes.
So how does this work? The brine close to the surface is warmed by the sun, causing some water to evaporate into the air. As more water evaporates, the remaining solution becomes saltier and denser than the fresher saltwater below it. This dense solution then sinks while less dense water rises to replace it, creating convection rolls that squeeze against neighboring cells. The researchers saw this happening in the soil in the lab and analyzed samples taken from salt deserts. They also captured time-lapse videos showing this phenomenon happening at Owens Lake in California. This proposal makes sense because it explains why there is uniformity across different regions and why each cell is 1 to 2 meters (3.3 to 6.6 feet) in size. It can also help scientists understand how much mineral-packed dust these deserts are giving off, which is important for understanding cloud formation rates and how minerals are transported through air to oceans.
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Although wind blowing over salt deserts creates atmospheric dust, understanding processes like this will help us better understand desert environments. According to physicist Lucas Goehring from Nottingham Trent University in the UK, "What we've shown is that a simple, plausible explanation is there but hidden beneath the ground." This discovery is a great example of curiosity-driven basic research as physicist Jana Lasser from Graz University of Technology (TU Graz) states: "Nature presents us with an obvious and fascinating puzzle that stimulates our curiosity and thereby prompts us to solve it – even without any direct further possibility of application in mind."
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