According to Chinese state media, the round block of ice formed by the natural phenomenon is about 20 feet in diameter.
       In a video shared on social media, the frozen circle is seen gradually rotating counterclockwise over a partially frozen waterway.
       It was discovered on Wednesday morning near a settlement on the western outskirts of the city of Genhe in the Inner Mongolia Autonomous Region, according to China’s official news agency Xinhua.
       Temperatures that day ranged from -4 to -26 degrees Celsius (24.8 to -14.8 degrees Fahrenheit).
       Ice disks, also known as ice circles, are known to occur in the Arctic, Scandinavia, and Canada.
       They occur at the bends of rivers, where the accelerating water creates a force called “rotating shear” that breaks off a piece of ice and spins it.
        Last November, the residents of Genhe also faced a similar scene. The River Ruth has a smaller ice disk two meters (6.6 ft) wide that appears to be spinning counterclockwise.
       Located near the border between China and Russia, Genhe is known for its harsh winters, which typically last eight months.
       According to Xinhua, its average annual temperature is -5.3 degrees Celsius (22.46 degrees Fahrenheit), while winter temperatures can drop as low as -58 degrees Celsius (-72.4 degrees Fahrenheit).
       According to a 2016 study cited by National Geographic, ice disks form because warm water is less dense than cold water, so as the ice melts and sinks, the movement of the ice creates whirlpools under the ice, causing the ice to spin.
       The “Whirlwind Effect” slowly breaks down the ice sheet until its edges are smooth and its overall shape is perfectly round.
       One of the most famous ice disks of recent years was discovered early last year on the Pleasant Scott River in downtown Westbrook, Maine.
       The spectacle is said to be about 300 feet in diameter, making it possibly the largest spinning ice disk ever recorded.
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