Since 1969, humans have been aware of bizarre ice rings forming in Lake Baikal, but for decades the exact mechanism as to how these strange structures arose remained unclear. In a recent study published in the journal of Limnology and Oceanography, researchers have finally cracked the source of these unusual spectacles.
At around 25-30 million years old, Lake Baikal is one of the world’s oldest lakes, and with a maximum depth of 1,642 meters (5,387 feet), it is, by volume, the largest freshwater lake in existence. Found in Siberia, Russia, it contains approximately 23,615.39 cubic kilometers (5,670 cubic miles) of fresh water, which amounts to more than all of the North American Great Lakes combined.
Throughout the year, the water temperature of the lake ranges quite dramatically. In the summer, the surface layer can be as warm as 16°C (61°F) in some areas, but the surface freezes for just over four months from early January to May. On average, the ice is about 0.5 to 1.4 meters (1.6 to 4.6 feet), but in some areas where there are hummocks (a knoll of ice that rises above the surface), it can be as thick as 2 meters (6.6 feet).
The lake has long been famous for the puzzling ice rings that appear during the winter months that are so vast they are visible from space. In fact, it was thanks to the help of NASA scientists that the mystery of these enormous spectacles was finally solved. Using data collected from satellites and sensors dropped into the lake, it was discovered that warm eddies deep below the frozen lake’s surface were creating a warm flow of water in a clockwise direction, even in the cooler months. The strength of the current is weakest in the center, where the surface ice remains frozen, but the stronger current on the outside of the eddy can thaw the ice, creating these astonishing formations visible from above.
While beautiful, the rings can prove perilous for the drivers who take their vehicles across the frozen lake, as despite being apparent from the perspective of satellites, they are a lot harder to spot at ground level. As a public service, Alexei Kouraev, an assistant professor at the Laboratory for Studies in Spatial Geophysics and Oceanography (LEGOS) at the Federal University in Toulouse, France, routinely updates a website with his team of researchers identifying the locations of newly formed ice rings.
The exact cause of this warm deep-water eddy formation is not yet understood, and research is continuing to try and further understand this phenomenon. Existing data indicates that water flowing in from other rivers and wind patterns could have a part to play, and that they likely form in the autumn months before the ice is frozen. For now, this ancient and cavernous lake still holds many secrets.