P*olar vortex* (also known as a *polar cyclone*, *polar low*, or a *circumpolar whirl* <http://en.wikipedia.org/wiki/Polar_vortex#cite_note-glossvortex-1>) is a persistent, large-scale cyclone located near either of a planet's geographical poles. On Earth, the polar vortices are located in the middle and upper troposphere and the stratosphere. They surround the polar highs and lie in the wake of the polar front. These cold-core low-pressure areas strengthen in the winter and weaken in the summer due to their reliance upon the temperature differential between the equator and the poles.
More click on following link http://en.wikipedia.org/wiki/Polar_vortex 2014 North American cold wave The breakdown of the polar vortex and subsequent southward movement of tropospheric Arctic air was caused by sudden stratospheric warming (SSW),<http://en.wikipedia.org/wiki/2014_North_American_cold_wave#cite_note-12>a phenomenon discovered in 1952. NASA states, "A major midwinter SSW event occurs when polar stratospheric temperatures increase by at least 25 K in one week, and the zonal-mean zonal wind at or near 10 hPa (at about 30 km altitude) reverses direction and becomes easterly north of 60° N."<http://en.wikipedia.org/wiki/2014_North_American_cold_wave#cite_note-GMAO-13> More on following url http://en.wikipedia.org/wiki/2014_North_American_cold_wave With best wishes S Chander -- You received this message because you are subscribed to the Google Groups "Thatha_Patty" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/groups/opt_out.
