Bizarre ‘ice rings’ on one of the world’s oldest and deepest lakes have left scientists baffled for decades – until now.
Using satellite data and sensors, experts have determined that the stunning formations on Lake Baikal in Siberia are a result of warm eddies, or warm water flowing in clockwise direction.
The swirling currents are stronger around the edges, allowing the ice to melt, but are weaker in the center which result in the area staying frozen.
Researchers are still investigating the cause of the swirling warm water, but data suggests they likely formed from wind patterns and the inflow of water from other rivers.
Alexei Kouraev, a hydrologist at the University of Toulouse, said in a NASA statement: ‘Results of our field surveys show that … there are warm eddies that circulate in a clockwise direction under the ice cover.’
‘In the eddy center, the ice does not melt – even though the water is warm – because the currents are weak.’
‘But on the eddy boundary, the currents are stronger, and warmer water leads to rapid melting.
Nizhneye Izgolovye Cape, where the image was taken, is one of the most common places for ice rings to occur.
Of the 57 rings detected on Baikal, about 13 formed in this area.
According to Kouraev, this is a prime area because an underwater canyon tends to ‘trap’ eddies in this area.
‘People often drive a direct line between Nizhneye Izgolovye Cape and Khoboy Cape,’ he said, ‘but we strongly advise that they take a more southerly route to avoid the frequent ice rings in this dangerous region.’
During the study, Kouraev and his team took the water temperature near the ice rings using a range of sensors at a depth of 700 feet.
They found the water in the eddies was two to four degrees Fahrenheit warmer than the surrounding water.
The team also discovered that the eddies have a lens-like shape, something found in oceans and rarely in lakes.
Most of the ice rings appeared in March or April, but can appear as early as January or as late as May.
The average ring is about three to four miles in diameter , which is far to large to be seen on the ground – which is why the team decided to check them out from space.
Ice rings have formed on Lake Baikal since at least 1969, with some last just a day to a few months.