I’m sick of winter.
It’s the right time of year for that statement. It’s early March and I’m ready for signs of spring. Unfortunately, we’re expecting up to a foot of snow tomorrow. It’s the right time of year for that as well.
I want green, but it looks like I’ll have to wait. So, I thought I’d write about the Polar Vortex. If the weather is going to be nasty, might as well know something about it.
The first thing to know is that weather (remember the difference between weather and climate) is created by air movement. Air moves around due to changes in temperature and pressure. The sun is hotter at the equator than at the poles. That temperature gradient alone would tend to move air in a North – South direction, but because of the earth’s rotation the air is also pushed in an East – West direction. This, along with the temperature difference between land and ocean, changes in terrain and a myriad of other factors causes air to flow in all directions in vaguely typical patterns. The jet streams, for example are generalized air flow patterns, so are the polar vortices.
A Polar Vortex is an area of low pressure centered over each Pole. The vortices are always there, but they strengthen and weaken depending on the temperate differences between the cold, dry polar air and the warm, moist air coming from the Gulf jet stream. The Polar Vortices are stronger in the winter and weaker in the summer. Whatever the season, the vortex is banded with a rapidly moving jet stream. When the vortex is strong the jet stream remains tightly bound around the pole, but when the difference in the temperature between interacting air masses is great, the jet stream can dip South (North in the case of the Antarctic) bringing the cold polar air with it.
Since the strength of the vortex is temperature dependent it is inevitable that climate change will have an impact. This year we had several weeks of temperatures well below zero. It hit 30 below at one point. I think that’s the coldest I’ve ever experienced. While no specific weather event is “caused” by climate change I think it’s safe to say our winters are altering.
Now I’m going to go out and walk along the edge of the field where the snow has melted. Today I’ll pretend it’s spring.
I’ll get my snowshoes back out tomorrow.
Thanks for reading,
March 6, 2018
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