Decipher the mysterious sand dune

Across the deserts, sand is swept up not only by the wind, but also by strong electric fields that appear near the surface, pushing sand particles into the air. By taking into account this electric field, researchers say they can create better climate change models and even explain the characteristics of dust on Mars.

Scientists have long been unable to explain why the sand rolling in the desert does not rise higher when the wind blows stronger. But when the University of Michigan research team - for the first time - took into account the role of charge in the bouncing of particles, they matched the model with their observations.

When the wind blows sand on the surface of the earth, friction causes sand particles to " pick up " loose electrons on the ground, making them negative and leaving a positively charged surface.

View of Egypt's Great Sand Sea, seen from the Plateau of Gilf Kebir in the Sahara.(Photo: LiveScience)

" It's like when you brush your cat's fur and see tiny rays, or rub a balloon over your head that makes hair stand up, " said Jasper Kok, a graduate student in applied physics at the University of Michigan. , the research leader, said.

This charge separation creates an electric field that can be as strong as 100,000 to 200,000 volts per square meter at a position of 1 centimeter from the surface. This electric field draws more grains of sand into the air because the positive particles on the surface are highly attracted by the suspended particles in the air.

This electric field also explains why the jumping sand particles do not rise higher when the wind blows. "We now think that as the wind speed increases, the electric field will increase, and the negative negative charge of the particles will cancel each other out ." As a result, despite strong winds, sand is just the ground.

This finding is rated very important for climate science, because it can better explain the occurrence of atmospheric dust, and open up the light of the physical properties of processes. the same, similar.

T. An