The Arctic Ocean used to contain a huge ice mass that helped to lock the North's coldest air in a vortex near the North Pole.
But that ice is mostly melted, and the vortex is now unstable, sometimes moving thousands of miles south.
This is part of climate change.
The Arctic Ocean used to contain a huge ice mass that helped to lock the North's coldest air in a vortex near the North Pole.
But that ice is mostly melted, and the vortex is now unstable, sometimes moving thousands of miles south.
This is part of climate change.