New computer model explains faltering jet stream
Scientists in Germany have applied machine learning to model the weakening of the jet stream that is partly responsible for extreme weather events, including the long cold winter of 2019 that held much of North America and Europe in an icy grip.
It's a strange irony that the warming of the Arctic has been bringing colder winters to regions farther south. This is partly due to a change in the jet stream, a river of air flowing at hundreds of km/h high up in the stratosphere that runs all the way around the northern hemisphere. It marks the boundary between the mass of cold Arctic air that caps the top of our planet and the warmer air around the middle.
Battleground between hot and cold air
The jet stream is the battleground between these two air masses as the warm air tries to move north and the colder pushes south. This boundary line is constantly moving, and like all rivers, the jet stream meanders, sometimes wandering south, allowing the cold air to drop down to the mid-latitudes, which happened last winter, or it can curve northwards, bringing warm air up from the tropics, producing hot, dry periods.
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