maximus otter
Recovering policeman
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Scientists have long observed smooth, repetitive patterns of stones and grooves that mark the ground in colder regions in the world. Each intricate design—including circles, orderly rows, and swirls—was created when stones are moved around when tiny, thread-like sprouts of ice emerge from the freezing ground. As these so-called "ice needles" freeze and then melt, they create astonishing patterns similar to those in Japanese zen gardens. However, while researchers speculated that spikes of ice crystals could move soil and rocks to form the patterns, it hasn't been confirmed until now.
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Ice needles develop when the temperature in the air and the temperature of the moist soil are not the same. At night, some types of soil contract when temperatures drop. The water in the soil is then drawn upwards and sticks to the sides of narrow pores in the ground. As the water is drawn out of the Earth, the cold air freezes it, turning it into small sharp, crystal-like structures.
To create the swirls and ridges in a lab setting, the research team placed pebbles on top of a pan filled with wet, fine-grained soil and then froze and thawed the miniature landscape over and over, creating different conditions to see how the pebbles moved as the ice melted. Pins of ice poked through the soil like sprouting grass when the wet soil was not frozen, but the air temperature dropped below freezing. The needles grew several centimeters high, raising the pebbles off the ground. When the team increased the temperature, the stones fell off the ice and tumbled to one side.
Over time, researchers could see how the freeze-thaw process cleared patches of exposed soil, and eventually, stones shifted into clusters, creating larger patterns. In total, the team exposed the rocks and dirt to 30 freeze cycles during which the ice formed and thawed away. The group noted that stones on the flat ground formed the dizzying array of swirls and loops, while sloped ground formed neat rows of rocks.
Some experts suspect that a version of these freeze-thaw cycles may have created patterns observed on the surface of Mars. Soil on the Red Planet has shown evidence of tiny ice crystals, and as the soil on Mars heats up, it may expand only to contract after it begins to cool again. Though the process is more subtle on Mars, it could be enough to shift pebbles and dust over time.
https://www.smithsonianmag.com/smar...gid-landscapes-are-sculpted-by-ice-180978955/
maximus otter
Ice needles develop when the temperature in the air and the temperature of the moist soil are not the same. At night, some types of soil contract when temperatures drop. The water in the soil is then drawn upwards and sticks to the sides of narrow pores in the ground. As the water is drawn out of the Earth, the cold air freezes it, turning it into small sharp, crystal-like structures.
To create the swirls and ridges in a lab setting, the research team placed pebbles on top of a pan filled with wet, fine-grained soil and then froze and thawed the miniature landscape over and over, creating different conditions to see how the pebbles moved as the ice melted. Pins of ice poked through the soil like sprouting grass when the wet soil was not frozen, but the air temperature dropped below freezing. The needles grew several centimeters high, raising the pebbles off the ground. When the team increased the temperature, the stones fell off the ice and tumbled to one side.
Over time, researchers could see how the freeze-thaw process cleared patches of exposed soil, and eventually, stones shifted into clusters, creating larger patterns. In total, the team exposed the rocks and dirt to 30 freeze cycles during which the ice formed and thawed away. The group noted that stones on the flat ground formed the dizzying array of swirls and loops, while sloped ground formed neat rows of rocks.
Some experts suspect that a version of these freeze-thaw cycles may have created patterns observed on the surface of Mars. Soil on the Red Planet has shown evidence of tiny ice crystals, and as the soil on Mars heats up, it may expand only to contract after it begins to cool again. Though the process is more subtle on Mars, it could be enough to shift pebbles and dust over time.
https://www.smithsonianmag.com/smar...gid-landscapes-are-sculpted-by-ice-180978955/
maximus otter