If you were on a bridge overlooking a swiftly flowing creek then you would notice that twigs floating in the water did not move across the current. They are carried downstream along the edge of the current. Fast-moving concentrated flows have the effect of isolating one side of the creek from the other. This is true in the creek, and it is also true about jets streams in the atmosphere.
RickyRood, • 4:22 PM GMT on October 14, 2013
The vortex in Figure 1 is a barrier. The southern edge of vortex is a jet stream. Air on the two sides of the vortex often has different characteristics. Intuitively, there is colder air on the poleward side. The take away idea is that the edge of the vortex is a barrier. It’s not a perfect barrier, but air on one side is largely separated from the air on the other side. In the next blog, I will describe the difference between the strong and the weak case and its relevance to weather, climate, and perhaps, climate change.
RickyRood, • 12:50 AM GMT on October 03, 2013