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blnymph -> RE: Who is ready for some global warming? (1/7/2017 11:49:02 AM)
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To sum up about polar jetstreams:
Jet streams are caused by earth rotation and temperature differences.
They move more or less in wave lines over the northern (and in a kind of mirror image over the southern) hemisphere.
The way they rapidly transfer cold arctic air southward is one of the major influences of winter weather, snowfall intensity, storms etc.
Where these jetstreams hit land over northern America, Europe, northern Asia makes a lot of difference in regional distribution of cold arctic air, and snowfall.
While the Rocky Mountains running N-S do not block the arctic jet streams reaching out far south the European mountain ranges of Pyrenees-Alps-Carpathians spreading W-E usually block the spread of arctic jet streams, wherever they meet this barrier, to the mediterranean basin. So due to geography there usually is a more predictable N/S divide in winter temperatures, snowfall etc. on our side of the pond than on yours.
Circumpolar as well as tropic jetstreams have been more or less constant over longer time periods; this seems to change, maybe linked to the change in oceanic currents like the Labrador and Gulf stream or El nino/El nina.
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